The Merriam-Webster Dictionary states:
"Etymology: Middle English feith, from Old French feid, foi, from Latin fides; akin to Latin fidere to trust -- more at BIDE
1 a : allegiance to duty or a person : LOYALTY b (1) : fidelity to one's promises (2) : sincerity of intentions
2 a (1) : belief and trust in and loyalty to God (2) : belief in the traditional doctrines of a religion b (1) : firm belief in something for which there is no proof (2) : complete trust
3 : something that is believed especially with strong conviction; especially : a system of religious beliefs"
Personally, I stick to 1 b(1), meaning making the effort to keep my promise of practicing three times a week, and (2), meaning I try to be as sincere as possible, either as uke or nage.
No religious beliefs at all.