The 'Keys to the Kingdom' is the ability to preach the Gospel correctly.  The power of the word is that it always bare fruit, though you may not see it, in time wherever you sow it, it will bare fruit.  When you've had the anointing,  the Gospel ceases being about you, but about other people. Because then your job becomes about letting people know about the 'Fellowship of the Mystery'

Ephesians 3:9 And to make all men see what is the fellowship of the mystery, which from the beginning of the world hath been hid in God, who created all things by Jesus Christ:

What you sow in the fields of the earth, meaning into the minds of men, bares fruit, once they have found what has been hidden in the field. Remember what was said about eating unleavened bread.

Matthew 13:33 Another parable spake he unto them; The kingdom of heaven is like unto leaven, which a woman took, and hid in three measures of meal, till the whole was leavened.

Consider this, St' John of Revelation was imprisoned on an island call Pat-mos, which means mortal.

Job 7:11 Therefore I will not refrain my mouth; I will speak in the anguish of my spirit; I will complain in the bitterness of my soul.

And all people will do, since the mystery of the Gospel speaks against the works of the soul. To be clear, the battle of Armageddon is against the works of the soul.

Revelation 10:10 And I took the little book out of the angel's hand, and ate it up; and it was in my mouth sweet as honey: and as soon as I had eaten it, my belly was bitter.

All people are representative of what he brought via revelation in the book of revelation.

Revelation 8:11 And the name of the star is called Wormwood: and the third part of the waters became wormwood; and many men died of the waters, because they were made bitter.

And like wormwood it will make that third part of man bitter. Why, because people read revelation in an earthly fashion, and instead think of the destruction of this world, especially the sinners (Just who do you think Jesus was calling?), instead of the redemption of all people back into the Kingdom of Heaven.

Zechariah 13:9 And I will bring the third part through the fire, and will refine them as silver is refined, and will try them as gold is tried: they shall call on my name, and I will hear them: I will say, It is my people: and they shall say, The Lord is my God.

The third part of man being the spirit, the second part of man being the soul, and the first part of man being the body.

Romans 10:15 And how shall they preach, except they be sent? as it is written, How beautiful are the feet of them that preach the gospel of peace, and bring glad tidings of good things!

Again, good news achieves nothing but good, when it is ready, and as said above, is sent, not by man's will, but Gods, and always prospers.

Isaiah 55:11 So shall my word be that goeth forth out of my mouth: it shall not return unto me void, but it shall accomplish that which I please, and it shall prosper in the thing whereto I sent it.

Because it also enables people to know the Father, as said above, nothing is void. Why do you think it is called the good news? Because nothing but good comes from hearing it. Think hard on that, because if something is bad that comes from something that is supposed to be good, it is bad, and guess what? that includes your own thoughts.

Matthew 16:19 And I will give unto thee the keys of the kingdom of heaven: and whatsoever thou shalt bind on earth shall be bound in heaven: and whatsoever thou shalt loose on earth shall be loosed in heaven.

But not like in the religious way where one believes they can convince, save, convert and persuade men. Since that is manipulation, and that is bad.

John 3:8 The wind bloweth where it listeth, and thou hearest the sound thereof, but canst not tell whence it cometh, and whither it goeth: so is every one that is born of the Spirit.

The spirit is unseen, and awakens in a person like a thief in the night.

Matthew 13:44 Again, the kingdom of heaven is like unto treasure hid in a field; the which when a man hath found, he hideth, and for joy thereof goeth and selleth all that he hath, and buyeth that field.

What the 'Keys to the Kingdom' enables one do is to sow spiritual seeds into the field, so that when another's time has come, they will also seek and find that treasure hidden in the field.

Galatians 5:8-9 This persuasion cometh not of him that calleth you. A little leaven leaveneth the whole lump.

Revelation, your understanding given to you from the Father is that good treasure, and with that treasure you'll be able to sow seeds into the world. Again, that is preaching the Gospel. The Bible is not the gospel in of itself, so wildly quoting scripture in isolation isn't going to achieve much.

Matthew 22:14 For many are called, but few are chosen.

Everyone for the most part and read and hear with their physical body, few of the very few can read, hear and see with their spirit, and few are chosen, because few recognise the spirit.

2 Timothy 3:16-17 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: That the man of God may be perfect, thoroughly furnished unto all good works.

However the scriptures do instruct the spirit, but only once it has some understanding of the spirit, since prior to receiving revelation, the mystery of the Gospel has been hidden to the spirit, because the spirit, meaning your own mind doesn't know itself and only knows the thoughts of the heart, which gets its knowledge from this world, and from the wisdom of men.

Ephesians 3:2-4 If ye have heard of the dispensation of the grace of God which is given me to you-ward: How that by revelation he made known unto me the mystery; (as I wrote afore in few words, Whereby, when ye read, ye may understand my knowledge in the mystery of Christ)

Which why things are written in similitude's and parables, because the mystery of the Gospel, being a mystery is obviously hidden and can only be revealed by God. But first a person must seek him first within, with their spirit.

1 Corinthians 2:9-11 But as it is written, Eye hath not seen, nor ear heard, neither have entered into the heart of man, the things which God hath prepared for them that love him. But God hath revealed them unto us by his Spirit: for the Spirit searcheth all things, yea, the deep things of God. For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God.

So, all people need to receive the spirit of God, to be taught about the things of God, because people can't be persuaded at all by men, especially about the spirit.

1 John 2:27 But the anointing which ye have received of him abideth in you, and ye need not that any man teach you: but as the same anointing teacheth you of all things, and is truth, and is no lie, and even as it hath taught you, ye shall abide in him.

You have to be in the Father, and the Father's spirit in you, which will guide you to the knowledge of all things, which are added via revelation.

Matthew 6:33 But seek ye first the kingdom of God, and his righteousness; and all these things shall be added unto you.

However, before all that, when people read the scriptures and hear about the Kingdom, there is a veil upon the hearts and mind of the people. When reading the word, they'll only see similitude's, and parables, and not understand anything outside of their own understanding. They can only believe, but they cannot know, and thus they cannot preach the Gospel, because they haven't received those 'Keys to the Kingdom' which enables them to be sealed with the 'Holy Spirit'.

Ephesians 1:13 In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise,

Yes, people claim to believe, but they simply don't, because they haven't heard the Gospel to believe in it in the first place. They only believe in men's words about God, and about Jesus. In short in their faith, in their religion.

James 2:1 My brethren, have not the faith of our Lord Jesus Christ, the Lord of glory, with respect of persons.

Meaning to say, people do not learn correctly about Jesus and God through the faith of men, nor through the knowledge of men.

James 2:9 But if ye have respect to persons, ye commit sin, and are convinced of the law as transgressors.

Respect no man when it comes to the knowledge of the spirit, and certainly don't follow them. All are sinners here, so learning from sinners is counterproductive.

Ephesians 6:19 And for me, that utterance may be given unto me, that I may open my mouth boldly, to make known the mystery of the gospel,

The Gospel is a mystery that is revealed by God, when a person is ready to hear it.

Luke 1:17 And he shall go before him in the spirit and power of Elias, to turn the hearts of the fathers to the children, and the disobedient to the wisdom of the just; to make ready a people prepared for the Lord.

The whole point of being given the 'Keys to the Kingdom' is prepare people and make them ready to receive the word of God. Give what you have.

Psalm 10:17 Lord, thou hast heard the desire of the humble: thou wilt prepare their heart, thou wilt cause thine ear to hear:

The Prophets and the Apostles did that, being the foundation, and Jesus was the cornerstone on which all understand of the spirit is built. And the people who the prophets came to, they rejected, and because of that what Jesus taught was rejected.

Mark 12:10 And have ye not read this scripture; The stone which the builders rejected is become the head of the corner:

That is the knowledge of the Kingdom. However, without doing as Jesus taught, like his Apostles did, they can only take the Apostles words at face value, and around their words man has created a religion. Worshipping the words of the disciples instead of aiming to become disciples themselves, just in the same way Jesus did.

Luke 14:33 So likewise, whosoever he be of you that forsaketh not all that he hath, he cannot be my disciple.

Who last time anyone looked, didn't create a church for all people to worship in. Which is of the world, what is also of the world is man's own knowledge, and it is that knowledge, the wisdom of this world that all men refuse to forsake.

1 Corinthians 2:6-8 Howbeit we speak wisdom among them that are perfect: yet not the wisdom of this world, nor of the princes of this world, that come to nought: But we speak the wisdom of God in a mystery, even the hidden wisdom, which God ordained before the world unto our glory: Which none of the princes of this world knew: for had they known it, they would not have crucified the Lord of glory.

And it still isn't known by men. After all, if the prophets and righteous men of the day inspired by the spirit of God to write the scriptures themselves didn't know the mystery of God, how is anyone else supposed to, without being specifically chosen by the Father?

Matthew 13:17 For verily I say unto you, That many prophets and righteous men have desired to see those things which ye see, and have not seen them; and to hear those things which ye hear, and have not heard them.

And even they couldn't hear nor see those things his disciples heard because the knowledge of the spirit wasn't in the world until Jesus came to teach about it, letting the world know about the Father.

John 17:25 O righteous Father, the world hath not known thee: but I have known thee, and these have known that thou hast sent me.

It is that knowledge of the spirit that allows people see and hear the parables and similitude's clearly, and then know truth.

Hosea 12:10 I have also spoken by the prophets, and I have multiplied visions, and used similitudes, by the ministry of the prophets.

Parables and similitude's which are all the about the spirit, hidden skilfully within the scriptures, which none can see, neither can they understand unless they have the Holy Spirit within them teaching them, and revealing their meaning.

Ezekiel 20:49 Then said I, Ah Lord God! they say of me, Doth he not speak parables?

As he said, his words were not pertaining to the flesh, which is where all people err, using their own understanding to interpret the scriptures.

2 Peter 1:20 Knowing this first, that no prophecy of the scripture is of any private interpretation.

Without the 'Keys to the Kingdom' then people can only interpret the scriptures in earthly terms, deceiving themselves to be wise in the knowledge of the scriptures, when the sad truth is they know nothing. People can spend sixty six years being taught, reading, learning and studying the Bible. But with God, anyone can learn within a fraction of a second more than they.

John 6:63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.

Because they can only consider the flesh and the teachings of men, since that is all people will know before renewing their spirit, quickening it with the revelations gifted from the Father which brings the understanding of the spirit. Knowledge of the spirit is veiled behind the words all men attribute to the flesh.

Matthew 13:13 Therefore speak I to them in parables: because they seeing see not; and hearing they hear not, neither do they understand.

One of the seals of the book is realising the following.

Hebrews 10:1 For the law having a shadow of good things to come, and not the very image of the things, can never with those sacrifices which they offered year by year continually make the comers thereunto perfect.

One of the things he taught his disciples when he opened their understanding of the scriptures (The Law and the Prophets).

Luke 24:44-45 And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me. Then opened he their understanding, that they might understand the scriptures,

And until that understanding is opened in all individuals.

2 Corinthians 3:14-16 But their minds were blinded: for until this day remaineth the same vail untaken away in the reading of the old testament; which vail is done away in Christ. But even unto this day, when Moses is read, the vail is upon their heart. Nevertheless when it shall turn to the Lord, the vail shall be taken away.

Understand real clear who gives you that understanding.

Matthew 24:4 And Jesus answered and said unto them, Take heed that no man deceive you.

If it is not of God, it is from man, and God is a spirit.