In this verse “fear” is the fear of the final judgment. God’s love for me as a believer means I don’t need to fear the wrath I deserve as a sinner, because my sins have already been forgiven through Jesus’ act of love of dying on the cross.

But what is this perfect love? 

Let’s back up to verses 16 and 17:

“So we have come to know and to believe the love that God has for us. God is love, and whoever abides in love abides in God, and God abides in Him. By this is love perfected with is, so that we may have confidence for the day of judgment, because as he is so also are we in this world.”

Perfect love is Christ’s death for me. If I believe in Him and He’s my Savior then I don’t have to fear God’s wrath in the final judgment.

Let’s check out the Greek translations of these verses:

Verse 16 (Greek translation): And we know and have believed the love which God has in us. God is love, and the one remaining in this love in God remains, and God in him remains.

Verse 17 (Greek translation): By this has been perfected the love with us, that we may have confidence in the day of judgment, because just as that one is also we are in this world. 

Verse 18 (Greek translation): Fear is not in this love, but the perfect love casts out the fear, for fear has to do with punishment, and the one fearing has not been perfected in love.

And what about abide in the English translations? 

“Abide” also appears in verse 12: “No one has ever seen God; if we love one another, God abides in us and his love is perfected in us.” According to The New Strong’s Expanded Exhaustive Concordance of the Bible “abide” is a primary verb, meaning to stay (in a given place, state, relation or expectancy); remain, dwell, continue, tarry, endure, be present.

Going back to verse 16, if we abide in love then we abide in God, and God abides in us. When we remain in love, we stay with God. When we endure in love, we endure in God. I don’t know about you, but that sounds pretty amazing to me.