what are we supposed to say again when christians ask us where we get our morality?

[GrandizerII]

No, I am sincere. Many people have learnt moral lessons through religious influence. When one takes away religion entirely, it can be hard to see the logic of keeping any subsequent morality. The only real atheistic reason for understanding or forgiveness that I can see, is if everything is physical and pre-determined anyway... but then that also negates my own responsibility or free will and so everything I do is essentially inconsequential, including murder.

If most of are predetermined to have morals and be morally accountable for the things we say and do, then this is a problem how?

Determinism does not preclude responsibility if responsibility itself can also be predetermined.

Also, not sure if you've read the exchange between me and Stantler, but I show that even theists have to follow their own individual (and societal) moral rules due to a lack of access to a source of objective morality.