Faith is a journey, not a destination. All religious people have doubts, that’s the very nature of “faith”.
People who are absolutely certain that they are “right” and that they personally know the will of God make me very nervous.
I disagree with the following:
I always think of a large part of church work to be basically recruitment of congregation
A large part of the work of a minister/priest/rabbi/Iman etc is about serving their congregation and community.
They support families through the key stages of life births, marriages, illness and deaths.
They provide all sorts of counselling, education, advice and help people engage with community and council services.
They support, counsel and visit with the elderly, the sick, young Mums etc.
Help people whose marriage is in crisis, help those who are suffering stress or distress.
They do also evangelise of course but it’s not what they spend their time doing.
Some ministers (etc) will be able to carry on their work through a crisis of faith. Others may take a sabbatical or undertake a different role or further study. Some will leave their church all together.
Most ministers are pretty qualified and work very hard for not very much money. I’m not sure how many stick it out “just for the house” as you suggest when there other options open to them.
Every minister I’ve ever known has preached on the subject of doubt.