John 3:16 says it all. For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.
That's love! I don't have any children, so the closest thing I have to relate this to would be my husband. I love my husband more than anyone else, except for the Lord, of course. If I were asked to sacrifice him for someone else, do you know what my answer would be? NO WAY! I love my family, and I love my friends, but Jason is a part of me. We are one flesh. To give him up would be to give up a part of myself. It would be like ripping off a part of my own body. I couldn't do it.
Yet, that's exactly what God did for us. He loved us so much that He took a part of Himself and offered it as a sacrifice for our sins so that we didn't have to bear the penalty of those sins. Can you think of a better example of love? I can't.
Some would argue that God only sent His Son to die because He knew He would be resurrected in three days. Well, it is true that God knew Jesus would not stay dead. After all, that was His plan from the beginning. But still, do you think it was easy for God to watch His Son suffer? Don't you think it broke His heart to hear His Son scream, "My God, my God, why hast thou forsaken me?" Can you imagine how it must have felt for God to have to turn away from His Son at the time when His Son needed Him the most? Even if I knew I could have Jason back in three days, I wouldn't be able to witness such a horrible scene. I couldn't bear it, but God did. He put Himself and His Son through that torment because of His great love for us. If that's not enough to make us want to love Him in return, I don't know what is.