This is a postmodern sidestep when it comes to Christians describing what the Bible says. It's one thing to say, "The Bible is all fairytales" and another to say "The Bible is the Word of God, but it's all relative."
I am not assuming that MY version of health is the only true one. In a conversation with other Christians who are quoting scripture, I'm trying to discuss what SCRIPTURE says is healthy and unhealthy.
But at the end of the day, the blanket statement, "We all find comfort in what we can, and that's good" can be disproven with a couple of examples, and then we can discuss how that applies to the claims of the Bible. You seem to be assuming that the Bible is only as true as each person's interpretation (i.e. only as true as it is true for any specific person", or else you're assuming that it may ultimately be true but that none of us can ascertain the underlying truth of the claims. I am assuming that Christians can discuss the Bible as an authoritative source, and for anyone who can't/won't believe that, it would be a completely different conversation.