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

[GrandizerII]

i think the christians have a point here

from what i can tell most atheists still get their morality from fear of the law or being publicly shamed, a lot of which was originally to do with religious intervention

Only a psychopath/sociopath or the like would think that way. So this does not apply to most atheists or most people for that matter.

an example would be murder

i can't really think of a reason not to murder everyone if there wasn't those consequences to it

Doesn't matter what the reason is (at least practically speaking). People are subconsciously conditioned to see killing, in most cases, to be wrong regardless.