Sumerian Religion

I was out witnessing and a man said to me "… You." I then preached against him and he turned around and walked to where I was standing and wanted a debate. I had mistaken him to be New Age or Scientology, but he holds to some Sumerian religion. After hearing him out and he said he would read the More than a Carpenter tract that I gave him, he eventually apologized for cussing me out and I got his email. Usually I use the LAW for the proud, and grace for the humble, but he was not ready for the law, so once he reads the tracts I will send him an email and use the LAW.

Anyone know much about the Sumerian religion? I looked it up on Google but do not fully understand what I read. I am no apologetics expert like a Hank Hanagraaf or Josh McDowell so perhaps I should ask them.