Sure they can. No-one is spiritually perfect. We're all a work in progress.
Yes I agree but my religion teaches that the spiritual side of man is only good and never does harm to anyone. It is the lower nature, the animalistic nature (ego, lower self) of man, which , if we allow to control us, causes wars and bloodshed etc So if a mans higher nature dominates his life he becomes a saint or true believer while if he allows his lower nature to dominate he becomes a hypocrite and lower than an animal.
A true believer of any Faith i believe, is he who’s higher nature dominates not self and passion. So my religion states that it doesn’t really matter what we call ourselves that we are known by our deeds not our words.
That’s why I pointed out that a Muslim, according to the Quran is a person who lives the life according to the Quran not just in name only but loves and respects all life otherwise he is not a true Muslim.
In the Bible it puts it in a nutshell. It says something like ‘ he who says he loves God but hates his human brother is a liar’. So to me a person can only validate and verify who they claim to be by their deeds not their words.