She has a faithy personality.

Her last name is Faithfull.

She is the faithfulest friend I have ever had.

She is the faithfullest friend I have ever had.

The faithheads gathered at the church for Sunday service.

She is a devoted faithist.

Faithism is a belief system that promotes religious devotion and worship.

Many faithists gather at the temple every Sunday.

Her faithlessnesses towards her friends caused them to lose trust in her.

Her faithworthiness was unquestionable.