Is this workplace harrasment ? What can I do about it ?

Talk to the section supervisor. Say something like, "I'm very excited to get a chance to test some of the higher risk samples, but Mr. X doesn't seem ready for me to do it yet. How can I show him that I can handle these tests?" You're seeking advice, and you're being diplomatic. If you want to be more direct, you could add, "based on some of his comments, I think my religion makes him uncomfortable."