There are many within the church today who's evangelism tactics are using Revelation 3:20 to get people to say a prayer and invite Jesus into their hearts, but is this method true Biblical evangelism that leads to true Biblical salvation? Let me show you why it's not. Revelation 3:20 says "Behold, I stand at the door and knock. If anyone hears my voice and opens the door, I will come in to him and eat with him, and he with me." There are at least several reasons why using Revelation 3:20 to get people to ask Jesus into their heart is seriously flawed.
First we need to remember that context is king when interpreting Scripture and that Scripture interprets Scripture but the context in Revelation chapter three tells us that Jesus is knocking on the door of the church, and more specific the door of "the church in Laodicea" .v14 which is not only a real church but also the last and terrible state of the church age before Christ returns and not the human heart in general. Jesus is not knocking on the door of someone's heart hoping they will let Him in, but rather "the Judge is standing at the door" (James 5:9) "Christ Jesus, who is to judge the living and the dead" (2 Timothy 4:1) and what will be the state of this "lukewarm" .v16 church age when He returns? He tells us in verse 17 that it's rich, prosperous, and think that they have need of nothing but in reality they are actually wretched, pitiable, poor, blind, and naked. What a description of the modern church in which we see all around us. Remember that this is the letter to the seven churches concerning the return of Christ. Mark how Christ ends this letter to the seven churches "He who has an ear, let him hear what the Spirit says to the churches’” .v22. To suggest that Christ is outside knocking on the door of someone's heart who won't let Him in is not only assuming a meaning on the text that is not there in it's original context but it does not present the omnipotent Lord of heaven and earth who "does all that He pleases." (Psalm 115:3) but rather a weak and needy Jesus who has no power to overcome your stubborn so-called free will.
Second the fact that repentance is an essential response of genuine conversion (Acts 2:38, Luke 5:32, Luke 13:3 etc.) is clear from Scripture and asking Jesus into your heart leaves out this most basic response and how can true Biblical evangelism leave out what the Bible calls a gift from God. (2 Timothy 2:25) It also leaves out the resurrection which is so crucial to Biblical salvation that you never find one public sermon in the Bible by the apostles where they fail to mention Christ resurrection. No resurrection in your gospel presentation equals no gospel.
Another reason Christ is not knocking on the door of your heart for you to let Him in is that He doesn't want to come into your old cold dead heart. For Ezekiel 36:26 tells us that He "will give you a new heart, and a new spirit I will put within you" it's the doctrine of regeneration where "one is born again" (John 3:3) and is made "a new creation" in Christ Jesus where "The old has passed away; behold, the new has come." (2 Corinthians 5:17) You see asking Jesus into your heart just adds Jesus to what you already got going on and that's not Biblical salvation, for you "were dead in trespasses and sins;" (Ephesians 2:1) and you need to "be made alive" (1 Corinthians 15:22). Also this view places man as the final decision maker of his own destiny and not Christ as the Creator of this "new creation". Salvation is a miracle brought about by a Sovereign God, for men's hearts are "in the hand of the Lord, as the rivers of water: he turneth it whithersoever he will." (Proverbs 21:1) The call to repent and believe the gospel is not a passive plea by a Jesus who would never go where He is not asked in hopes that He get's to have a personal relationship with you. No, it's a declaration of terms and conditions from the Almighty Merciful King of Heaven of your surrender that He commands you to obey, and you don't get to negotiate these terms. Your response to these terms to repent and believe the gospel is either, "He that believeth on him is not condemned:" or "he that believeth not is condemned already, because he hath not believed in the name of the only begotten Son of God." (John 3:18)
So what's the fellowship which Christ promises to the churches? It's simple it's a call for the church to be vigilant like the wise virgins in Matthew 25, to have our "flasks" .v4 full of His grace, and our "lamps trimmed" with His Word which gives "light to my path" (Psalm 119:105) and to be clothed in His righteousness "the righteousness of faith" (Romans 4:13) so that we don't "walk naked" (Revelation 16:15) and be ready for the coming of the "bridegroom" so that we may go "in with him to the marriage feast" .v10 and "as the bridegroom rejoices over the bride, so shall your God rejoice over you." (Isaiah 62:5) So press on brothers "toward the goal for the prize of the upward call of God in Christ Jesus. (Philippians 3:14)