In John 3:16, we see the highest example of love: God sacrificed His Son to pay for our sins.

The Greek word agape is the highest form of love.
1 Cor.13:4-7
 
Love wants what is best for others, no matter how they respond. It is a choice, an act of the will.

God loves all people, and wants them to be saved.
1 Tim.2:3-4; 2 Pet.3:9; Ezek.33:11
 
Why did God send His Son?

John 3:17-21 explains it was because all people were sinners. Rom.5:6-8, 3:21-26, 6:23

It was the only way God could offer salvation to the people He loved.
 
When anyone receives Christ as their Savior, God forgives their sin because the penalty is paid.

Salvation is a gift from God; there is nothing we could ever do to deserve it or earn it.
 
In 1 John 3:16, John remembered the words of Jesus, about 60 years earlier on the night of the Last Supper in John 15:12-13.