I am not sure I understand Terry's reply either. Sure you can include information from "Other" tags on Ancestor or Descendant Charts.
Exactly as you noted, go to the Data Types tab. Since the boxes are limited in size you can only include 9 entries in an Ancestor box, but one of these could be the Memo field from your Religion tag. Each of these 9 entries could be from a different tag type, but all people "of that type" will have the same 9 entries output.
As you mentioned, in both Male and Female ancestor box types, click on one of the unused Box contents numbered buttons. Now scroll down in the popup list to find the Religion tag and select "Religion* Memo". That will output the memo from the Primary Religion tag for the person.
You can only output the fields specified. But if you have entered their type of religion in the memo, this should work fine.