Stress test your ideas by exposing them to the most unfavourable assumptions. This is also good for rapid falsification of bad ideas.
Even if the Bible is completely true and representative, nihilism is still true.
When the Bible offers good advice, it's simply because "God" happens to know things you don't. Most of this takes the form of [want x, not y].
Problem 1: what you want is not up to you. You can't eat a candy and decide it doesn't taste sweet. You can't decide if you enjoy that sweetness or not. Using Bible cosmology, God is commanding you not to want the things he made you want.
Problem 2: if the advice is wrong it's inherently wrong. If you plain don't want x, no amount of avoiding y is going to be satisfying.
The advice can be correct if it can be re-cast in the form, [when your desire x and desire y conflict, you will be more satisfied by picking desire x]. This is a purely empirical question.
God is just a consciousness. Optimistically a big, wise consciousness that loves you, but this optimism is not well-supported by the Bible. That God wants something doesn't make you want it any more than the fact I want a thing makes you also want it.
In lay Christian theology, God is straight bullying you. His advice is 'good' not because you will be satisfied by taking it, but because he will punish you endlessly if you don't. He has to artificially reward the opposite as well. Technically following the advice is prudent but ultimately he's just the biggest asshole. No wonder so many fiction writers imagine getting more powerful than God; doing so would genuinely re-write the rules of the Christian universe.