The Armor of God
Christ showed that the religious teachers of His day, who had access to the knowledge of God's ways, had failed in this duty. "Woe to you lawyers! For you have taken away the key of knowledge. You did not enter in yourselves, and those who were entering in you hindered" (Luke 11:52Woe unto you, lawyers! for ye have taken away the key of knowledge: ye entered not in yourselves, and them that ere entering in ye hindered. Occasionally, the ministry has the sad duty to inform some that because of their choices and actions, the doors to the kingdom are being closed to them unless they repent. See 1 Corinthians 5 or 2 Thessalonians 3:14And if any man obey not our word by this epistle, note that man, and have no company with him, that he may be ashamed.
Revelation 3:7And to the angel of the church in Philadelphia write; These things saith he that is holy, he that is true, he that hath the key of David, he that openeth, and no man shutteth; and shutteth, and no man openeth; speaks plainly of Jesus having the key. In ancient Israel, the human king was in fact the steward of God, the true King of the land. Similarly, the divine Christ will be the steward of His Father's Kingdom. With that authority, Jesus could allow or disallow someone entrance into the Kingdom—but no man had or has that authority.
Christ's statement in Matthew 16:19And 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. He meant that His apostles had authority to represent Him, to teach as He taught them and to be instruments in helping people live the way the Kingdom of God. Christ still lends His authority to His true ministers today to do the same work. Sadly, many falsely claim this authority and misuse it.
The Armor Of God
I am a disciple
Wisdom for Men