The way we sometimes present the gospel would make this verse read more like this: “For we sinned so much that God gave His only begotten Son, that whoever believes in Him will quit sinning.”
We make the gospel out to be about our sin rather than God’s love. We send people down the Roman Road–“all have sinned” (Romans 3:23)–instead of up the Via Dolorosa–“He gave His only begotten Son” (John 3:16).