Bondley-
First I would recommend going to see yoru primary care physcian and having some routine blood work done to check your liver, kidney, and thyroid functioning, as issues with these organs can exaggerate the symptoms of OCD. After you get the all clear from the doctor, ask him/her to refer you to a cognitive behavioral specialist, as this is a therapist who specializes in treating anxiety issues and OCD. The therapist will help you to develop strategies to battle back against your obsessive thinking.
Common obssesive issues or thoughts include sex, violence, or in your case blasphemous thoughts about or towards God. You can also check the OC Foundations website, as they have listings of CBTs in different areas of the country.