“Christ died for OUR sins. Not the sins of Klingons or Vulcans or whatever is out there. “
I think the second part is indeterminate, and beyond the scope of the information given. Did he die for their sins too? Perhaps. Did he do it at the same event, or separately? Either is possible, and also not relevant to the first sentence. From Gods point of view, who is “us”? I think that’s for him to define.
You stated my points very well. Thanks.