Yes it is. You ask BitNow, I'll bet he/she says questioning doctrine is a sin.
"
The fear of the Lord is the instruction of wisdom; and before honour is humility."
- Pro 15:33
"
By humility and the fear of the Lord are riches, and honour, and life."
- Pro 22:4
Best regards.
So, that's a "yes"?
You need to ask a question to have an answer.
What is your question, maybe I can help you.