You seem to be confusing "scientific manner" with simply referring to science based topics in your argument. Just because you mention Evolution does not mean you are following a scientific methodology.
In addition, you keep making assumptions and using them as proof for your argument. For example,
"As such our species cannot be different to other animals w.r.t. having immortal souls or the ability to "sin" unless there was some sort of divine creation/intervention. Only we know our species was not created, we evolved."
You do NOT know there was no divine intervention. You cannot prove it. You are providing no evidence. And therefore, while you are mentioning 'science' in your argument, you are not able to draw any scientific conclusions from your argument.