The difference between questioning and doubting is action.
It’s okay to question something. You should ask questions. And yeah, there may be some apprehension before we decide to act (especially if you are doing something for the first time).
But doubt, on the other hand, is an inability to act. At its root, you’ll discover its fear.
Doubt your doubts before you ever doubt your faith.
[“My favourite word? It’s act.” – Ai Weiwei]