I may have posted about this before. But clearly the World At Large hasn't fully absorbed it, so I shall try again.
A "tenant" is someone who lives in housing owned by another person.
A "tenet" is an article of belief.
A "tenant of the faith" would be, I suppose, a person who lives in housing owned by a religious organization. This does not appear to be the meaning usually intended.
If you have trouble remembering, perhaps you could try noting that, if one is a tenant, one must worry about ants. (We certainly are.) Tenets, living in the ethereal realm of ideas, need not be concerned about such trifles.
Now, please, everyone, try to get it right this time.