My faith includes a belief in the Bible. I am not sure that it requires it. My RELIGION does have such a requirement, though.
On the “all faiths being valid” question, Unless God is much more universalist than my faith allows, there is only one “true” God or one “valid” God. I could be wrong, which is part of the nature of faith. So, if it turns out that it was Norse gods or Buddha, I guess I was wrong...
Is God really defined by your faith?