I had no idea that this was in the Bill of Rights of the Texas Constitution:

Article 1 – BILL OF RIGHTS
Section 4 – RELIGIOUS TESTS
No religious test shall ever be required as a qualification to any office, or public trust, in this State; nor shall any one be excluded from holding office on account of his religious sentiments, provided he acknowledge the existence of a Supreme Being. (Emphasis added)

Other states do this, too, although these clauses tend to not stand up to court challenges.

Still, why risk it? Should I ever run for office, I shall declare my faith in the Invisible Pink Unicorn: