Titus 3:3 For we ourselves were also once foolish, disobedient, deceived, serving various lusts and pleasures, living in malice and envy, hateful and hating one another.
When we talk about God loving us first we should always remember what we were like! We may not all have been as bad as some of the words that describe mankind, but we certainly were not angelic in our behaviour!
But even through that all, God chose to love us before we knew Him. He chose to love us in spite of all that we did wrong. He chose to love us knowing there was good inside of us.
Should we not have the same attitude toward others?