John 15:13 says,
“Greater love has no one than this, that one lay down his life for his friends.”
Jesus is saying to us, there is no love a person can have for another person that is greater than the act of giving up their life for that person. Although it is a concept hard to grasp, God loves all people so much that He came down to earth, God with us walking with man, in the body of Jesus, so He could pay the sin penalty in our place. Jesus dying on the cross was God Himself laying down His life for us, whom He calls friends.