Am I the only person who finds the entire concept of vicarious redemption to be utterly immoral (not to mention harmful)?

This morning we got to view a cartoon. It focussed on the relationship one has with his/her God and his/her dog. The similarity hi-lighted was that a person can mistreat his/her dog but will always be greeted with a wagging tail when one returns and changes one's treatment of the dog. The similarity with our relationship with God is that all one has to do to restore the relationship with God is return to the fold. An example: the parrable of the wayward son.

For those who adhere to christendom, there is no other way to get to your [imaginary] heaven and eternal life with your [imaginary] god but through the Christ character and his redemptive work on the cross.  There is no ambiguity about that within christianity.  (Now I know that there are a lot of people here who's beliefs are all over the map, but this is for those who accept the above to be true).

Please explain something that I wondered about many years ago (one of the things which actually lead me to abandoning christianity):