1 John 5:4:
For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith.
Notes on 1 John 5:4:
Mainstream Bibles are split over whether this should read “whatsoever” or “whosoever.” Young’s Literal Translation says, “…every one who is begotten of God doth overcome the word….” So who’s right, Young or the KJV? The Greek word pas could be translated either way. However, even in the King James Version, it is translated whosoever in Matthew 5:22 when Jesus talked about whosoever is angry with his brother without a cause, in Matthew 5:28 referring to whosoever looks on a woman to lust after her, in Matthew 7:24 about whosoever hears Jesus’ sayings and does them, in Matthew 10:32 about whosoever shall confess Jesus before men, in Mark 10:44 about whosoever among you wants to be the greatest, and in Romans 9:33 and Romans 10:11 about whosoever believes in Jesus shall not be ashamed. There are other places, but I’ll stop there because I’ve cited enough cases to make my point that whosoever (every one) is a good translation.
Jesus said that He has overcome the world (John 16:33), and you are in Him as a believer, so His victory is your victory. But the best proof of all that YOU (not just “things” born of God) have overcome the world is found in the very next verse!
1 John 5:5:
Who is he that overcometh the world, but he that believeth that Jesus is the Son of God?
So as a believer, you are already a world overcomer, whether or not you know how to walk in that privilege.
So why did Jesus talk about “he who overcomes” to all seven pastors in Asia Minor in Revelation chapters 2 and 3? I don’t think that there’s a contradiction. If you are in Christ, you are one who has overcome. If you stay in Christ, you continue to be one who has overcome. If you renounce Christ, you cease to be one who has overcome. Jesus was not saying that anyone had to do something that He already did.
See also:
How to Deal with the Devil
You Win!
The Temporary Curse
Objection: We Are Supposed to Glory in Tribulations and Count Them All Joy (Romans 5:3, James 1:2-4)