And let us consider how to spur one another on to love and good deeds. — Hebrews 10:24

John doesn't say love is God — he says God is love. Love isn't a definition of God; it's an attribute flowing from His character. And we know what love is because He loved us first and sent His Son. Anyone who abides in love abides in God, and God abides in him. This isn't sentimentality; it's the deepest reality in the universe — the God who is love has made His home with you.