The trick is to do so in a noncommittal way:
"Science can only deal with that which is testable and verifiable. . . ." clipped for brevity
I don't think you really need to delve into religion v. science. My biology teacher in high school gave a similar speech but left out any reference to religion. She just said that you are required to know what the theory of evolution says, but you don't have to agree with it. She even gave pointers on how to answer essay questions. All you need to do is start the answer with "The theory of evolution states . . ." and go from there.
If students keep pushing you could go on to say that if you go on to have a career in the biological sciences you will need to know how to apply the theory to your work. Go on to say that no current researcher is using anything other than evolution in their work when it deals with how biodiversity is produced in the natural world. Evolution is taught to prepare students for further education at the university level and for careers as scientists.