In the Catholic Church you always have the option to receive communion in the form of wine so there is a fully gluten free option.

My mom us a retired Episcopalian priest. She said there are gluten-free wafers you can get if someone in the congregation needs them. She also said that it doesn’t have to be a wafer, one of her priest buddies once consecrated a pancake to make a point that it doesn’t matter what’s being consecrated, it’s all God’s creation.

Note: I am not religious and do not hold these beliefs myself

Celiac technically isn’t an allergy, but yes. Some denominations will give you a gluten free communion wafer. Catholicism, however, requires one that contains wheat although it’s possible to get a very low gluten option that probably won’t trigger a reaction.