Hereby know we that we dwell in him, and he in us, because he hath given us of his Spirit. And we have seen and do testify that the Father sent the Son to be the Saviour of the world. He that feareth is not made perfect in love. Spirit-led obedience will provide evidence of our fellowship with God and love towards others. Verse 18 tells us that there is no fear in love.
Perfect love takes fear out of the heart.
Fear, however, has punishment. An unloving believer experiences torment because he feels guilty and is afraid to meet his Judge. You cannot have perfect love with this. But a Christian who loves has nothing to fear and can escape this torment. Because He loved us first.