that people are good at their base, there would be no need for religion
What is your argument for that?
Maybe people are hypothetically good but not perfect. Wouldn't there be a need still?
Do you really need the fear of eternal damnation to keep your evil in check?
The fear of damnation doesn't keep my evil in check at all anyway. It's the power of the Holy Spirit working in me that does that.
Romans 1-2 tell us that unbelievers know certain things about God, that He is, that He is creator, that He is invisible, that He is eternal, and that we stand condemned under His law. Put all those together, and that's scary, but it still doesn't lead us to repent and trust God. It leads us to greater evil. It's by unmerited mercy and grace that our lives and conduct become better.