It always puzzles me when the creationists think they are criticising evolution by calling it a "religion". Because, Surely, If being a "religion" makes evolution, According to their argument, Unsupported, facile, Not grounded in reality and false, it must be a bigger criticism of their own belief, A belief which actually is a "religion".
I mean, An evolutionist would never try to criticise creation by saying "well, creation is just another science based on factual evidence, Supported by practically every scientific discovery, rational and logical".
See, What they are trying to do with this type of approach is instead of defending their own position, They try to make ours seem as untenable as theirs. When in reality all they are doing is proving that even they think "religions" are inherently wrong, unsupported by evidence and, well, made up bullshit.
Make sure you pull them up on this next time they try it.