credo

A statement of a belief or a summary statement of a whole belief system; also (metonymically) the belief or belief system itself.

“You’re either with me or you’re against me” became Dany’s credo, and those against her were an ever-changing multitude to be determined solely by her whims.

The liturgical creed (usually the Nicene Creed), or a musical arrangement of it for use in church services.

Credo III is so beautiful!

Until the mid-1970s, however, most Catholic hymnals contained at least one musical setting of the creed […] By the 1980s hymnals having sung credos were mainly those devoted to "traditional" styles of church music […]