Intrusive and sexual thoughts popup into mind about god, when such thought come to mind i start prayers to avoid sin, help ?

Intrusive thoughts: "bad and unwanted thoughts" are just that. Individuals have many thoughts that they feel are ego-dystonic ( not what they want, but can't control.) it is only when "thoughts" turn to action that we have to be concerned. Try to relax you are ok. Keep up with your prayers, but consider talking to someone-- a therapist, who is an expert in this type of worry. Your clergy, if you feel comfortable.Md.

Sin: See that you have Obsessive Compulsive Disorder. Unfortunately the obsessive thoughts that ones gets are usually upsetting ones. That doesn't mean that you are a bad person but clearly it is very hard on you. The best answer is to treat the OCD - a combination of psychiatric medications and therapy such as cognitive behavioral therapy may be optimal. It is not your fault that you have OCD - so

See your md. : There are some real problems ( seizures, psych problems , etc ) that may manifest as intrusive thoughts. See your MD to make sure there isn't a medical cause of your symptoms. If clear, could then discuss with your religious leader.