I write this from the standpoint of my Christian culture, and my own past experiences, but it could perhaps relate to most religious beliefs.
Christians often associate mental well-being with closeness to God, resulting from time spent praying and studying the Bible, and collective worship.
Anything less than that can be seen as a personal weakness, and therefore personal responsibility for any difficulties or "backsliding".
Mental health problems are becoming better understood by Christians, but there remains some concern about the origins of such problems: Are they a result of sin? Of turning our backs on God? Lack of faith? Demon possession? Satanic attack?
Mental health problems are experienced by 1 in 4 of us, and they are therefore a normal human experience. However, the nature of the problem will lead us to doubt our faith, our role and responsibility in the development of the problems, and doubt God or our relationship with Him. Our relationships with our families, friends, church and God will inevitably suffer.
Others, who we might normally turn to, may not understand mental health problems. They might try to help but give unhelpful advice, or it might be easier for them to try to ignore our distress, or they might seem uncaring in some other way, causing us to feel even more isolated, fearful, depressed, even condemned.
You may feel that mental health professionals won't understand your difficulties as you believe the problems are due to your spiritual problems, but it's much more likely that your spiritual problems are due to your mental health problems.
Start by talking to your GP, and/or accessing Self Help Resources.
Cognitive Behaviour Therapy (CBT) is effective for a wide range of mental health problems, and will validate your Christian faith.
You will find many online self help resources for your faith by searching at Google.
Learn effective skills online
The Decider Skills for Self Help online course.