It's always possible they keep their faith private as commanded by Jesus.
Matthew 6:5 And when thou prayest, thou shalt not be as the hypocrites are: for they love to pray standing in the synagogues and in the corners of the streets, that they may be seen of men. Verily I say unto you, They have their reward.
6 But thou, when thou prayest, enter into thy closet, and when thou hast shut thy door, pray to thy Father which is in secret; and thy Father which seeth in secret shall reward thee openly.
Your prayer is to be private, but you should always express your faith in our Lord and proclaim the gospel to the lost.
Praying, yes. Giving to charity, yes. Sharing what the Lord has done for you? Go tell it on tbe mountain. I’ve been Saved for 52 years. It works for me.
It clearly refers to prayer, not faith.