Christ uses the past tense. It is not as though God only started to love lost men and women when Christ came into the world or when that individual first believed.
It is the Father’s love that would give the Son to be eternally changed for us, because from the time of the incarnation he would be everlastingly different in that he would wear human nature. How amazing that God the eternal Son, through whom the world was created, equal with the Father should take human nature eternally, to be my visible God in eternity and in glory.
Who is meant by the world? It refers, of course, to people. It refers to lost sinners. How could God love lost sinners? It was a love which took the form of pity and compassion. He could not love us as we were. He could not love our state as sinners, as rebels against him. He could not love our pettiness and smallness and our pride and our deceit. But he could pity us and have great compassion upon us. He could see what he could make of us, how he would put a new nature and a new heart in us, and how he would purify us in eternal glory. He could love us because he loved humanity, his special creation. Fallen though we were and defaced and ruined by the fall, yet we still had the power of reason. He loves every creature he has made in a sense, but man supremely, because he has been given the power of thought and reason, the power of creativity, the power of language, and the power to love in a deep and sophisticated way. He has given us moral consciousness, which he has not given to the animals. His desire was to restore humanity itself in Christ, with a people who were saved and forgiven and transformed. But it is particularly an individual love for people who he is determined to save that the verse speaks of.