>By definition if one is defending oneself, one is not committing murder.

Despite the fact that I think you understood what they were saying perfectly fine, you can substitute "killing someone" (or "taking another life", etc.) for "murder" in their above sentence if it helps you.

There’s a long standing theological distinction between murder and killing in the Bible. One I’m learning Quakers possibly disagree with.

I think I see your point. However, if the original poster didn't intend to substitute the defense motive with assault, then they could have made the substitution for us.