Why don't you read the millions of posts on this subject all over the internet. Take notes of the best arguments and create your own "argue-log".
An argeulog is an imagined conversation between two people. You write the script.
PRO: I believe in God
CON: Prove that God exists
PRO: blah blah blah
CON: blah blah blah
To infinity or ad nauseum which ever comes first.
Post your progress here. I'll be glad to read it and make suggestions.