I can help every pastor answer the first three questions honestly:
1. How do you know that your version of Christianity is the truth?
We don't know. We're relying on holy tradition.
2. How certain are you that the things you teach are correct?
Very certain but only because of faith; it's is believed because of faith and nothing more.
3. How well do you know the historical background of your holy book?
Most pastors know the origins of the Bible pretty well; they learn it in seminary, but the WAY it is taught is that it is God's will that the Bible was created. But again, this is one of the many LIES of "faith".
See the following article:
The 18 Biggest Lies the Church Uses to Deceive Billions