As long as you say, "in my opinion, X is the absolute truth" I think you're okay. ;o)
Seriously, all religious claims are, when you get down to it, statements of opinion. Any religious proposition begins with an implicit "I believe that..." If they were provable, there would be no need for faith.
What happens, though, is very often we forget that what we believe to be absolute truth are, in fact, statements of belief/faith. And that others, who do not share the same axioms we do, will not reach the same conclusions we do. If we focus solely on the "absolute truth" part, we can become very judgmental and condemnatory. It is in the axioms and conclusions where there is room for respectful dialogue (and respectful disagreement).