Albert Barnes Commentary 1 John 5:4

"For whatsoever is begotten of God overcometh the world: and this is the victory that hath overcome the world, [even] our faith." — 1 John 5:4 (ASV)

For whatsoever is born of God overcometh the world. The world, in its maxims, and precepts, and customs, does not rule him, but he is a freeman. The idea is that there is a conflict between religion and the world, and that in the heart of every true Christian, religion secures the victory, or triumphs. In John 16:33, the Savior says, "Be of good cheer; I have overcome the world." (See Barnes on John 6:33).

He obtained a complete triumph over him "who rules the darkness of the world," and laid the foundation for a victory by His people over all vice, error, and sin. John makes this affirmation of all who are born of God. "Whatsoever," or, as the Greek is, "Everything which is begotten of God," (pan to gegennēmenon); meaning to affirm, undoubtedly, that in every instance where one is truly regenerated, there is this victory over the world. (See Barnes on James 4:4; 1 John 2:15; 1 John 2:16).

It is one of the settled maxims of religion that every man who is a true Christian gains a victory over the world; and consequently, an equally settled maxim that where the spirit of the world reigns supremely in the heart, there is no true religion. But, if this is a true principle, how many professed Christians are there who are strangers to all claims of piety—for how many are there who are wholly governed by the spirit of this world!

And this is the victory. This is the source or means of the victory which is thus achieved. Even our faith. Faith in the Lord Jesus Christ, 1 John 5:5. He overcame the world, John 16:33, and it is by that faith which makes us one with Him, and that imbues us with His Spirit, that we are able to do it also.

(Note: For "whatsoever," an alternative is "whosoever." For "overcometh," compare 1 Corinthians 15:57.)