It's the most popular Bible verse and, in a sense, is a one-sentence synopsis of all the Scriptures.
For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.
(John 3:16 NIV)
Jesus, when He came to earth as a human, embodied love.
Probably no New Testament writer more frequently mentioned love than the apostle John.
7 Dear friends, let us love one another, for love comes from God. Everyone who loves has been born of God and knows God. 8 Whoever does not love does not know God, because God is love. 9 This is how God showed his love among us: He sent his one and only Son into the world that we might live through him. 10 This is love: not that we loved God, but that he loved us and sent his Son as an atoning sacrifice for our sins. 11 Dear friends, since God so loved us, we also ought to love one another. 12 No one has ever seen God; but if we love one another, God lives in us and his love is made complete in us.
(1 John 4:7-12 NIV)
Jesus loved by coming in the first place.
5 In your relationships with one another, have the same mindset as Christ Jesus:
6 Who, being in very nature God,
did not consider equality with God something to be used to his own advantage;
7 rather, he made himself nothing
by taking the very nature of a servant,
being made in human likeness.
8 And being found in appearance as a man,
he humbled himself
by becoming obedient to death—
even death on a cross!
(Phil. 2:5-8 NIV)
Jesus was in GOD's form and yet He humbled Himself to become a human and to die.
Regarding His choice to die for humanity's forgiveness, Jesus said:
14 “I am the good shepherd; I know my sheep and my sheep know me— 15 just as the Father knows me and I know the Father—and I lay down my life for the sheep. 16 I have other sheep that are not of this sheep pen. I must bring them also. They too will listen to my voice, and there shall be one flock and one shepherd. 17 The reason my Father loves me is that I lay down my life—only to take it up again. 18 No one takes it from me, but I lay it down of my own accord. I have authority to lay it down and authority to take it up again. This command I received from my Father.”
(John 10:14-18 NIV)
Jesus also taught love for one's enemies.
43 “You have heard that it was said, ‘Love your neighbor and hate your enemy.’ 44 But I tell you, love your enemies and pray for those who persecute you, 45 that you may be children of your Father in heaven. He causes his sun to rise on the evil and the good, and sends rain on the righteous and the unrighteous. 46 If you love those who love you, what reward will you get? Are not even the tax collectors doing that?
(Matt. 5:43-46 NIV)
And Jesus demonstrated this love, even to those who crucified Him.
29 “Woe to you, teachers of the law and Pharisees, you hypocrites! You build tombs for the prophets and decorate the graves of the righteous. 30 And you say, ‘If we had lived in the days of our ancestors, we would not have taken part with them in shedding the blood of the prophets.’ 31 So you testify against yourselves that you are the descendants of those who murdered the prophets. 32 Go ahead, then, and complete what your ancestors started!
33 “You snakes! You brood of vipers! How will you escape being condemned to hell? 34 Therefore I am sending you prophets and sages and teachers. Some of them you will kill and crucify; others you will flog in your synagogues and pursue from town to town. 35 And so upon you will come all the righteous blood that has been shed on earth, from the blood of righteous Abel to the blood of Zechariah son of Berekiah, whom you murdered between the temple and the altar. 36 Truly I tell you, all this will come on this generation.
(Matt. 23:29-36 NIV)
32 Two other men, both criminals, were also led out with him to be executed. 33 When they came to the place called the Skull, they crucified him there, along with the criminals—one on his right, the other on his left. 34 Jesus said, “Father, forgive them, for they do not know what they are doing.” And they divided up his clothes by casting lots.
(Luke 23:32-34 NIV)
Lastly, Jesus established the way by which we prove our love to Him.
15 “If you love me, keep my commands. ...
23 Jesus replied, “Anyone who loves me will obey my teaching. My Father will love them, and we will come to them and make our home with them. 24 Anyone who does not love me will not obey my teaching. These words you hear are not my own; they belong to the Father who sent me.
(John 14:15, 23-24 NIV)