I think christianity is to some extent an attempt at reforming Judaism. Christianity is actually a synchretic religion fusing Judaism with popular pagan religious memes.(virgin birth, dying and rising savior, personal savior, etc) The originators of christianity had a lot of Greco Roman influence and so subtly fused certain Greco Roman ethics, philosophies and mythologies into the religion.
By the first century, people who religiously subscribed to the Hebrew scriptures were growing in moral enlightenment due to the passage of time and exposure to other cultures, to the point that they came to see the God of the OT as being somewhat harsh even while being unwilling to drop him altogether. Christianity was created or shaped by that kind of environment. The kind, rule-bending, forgiving Jesus figure is an apologetics attempt at making over the image of the OT God; an attempt at saying in effect: 'We know these OT texts make God look really bad but he isn't really as bad as he seems because look how kind his son is. Look at his son. His son reveals his true nature so please don't get the wrong impression from OT texts that seem to suggest that he is harsh'