Human Nature

I once heard it said that all men are basically good, this saying I never quite understood. The thought has good intentions but I find the message rather pretentious. If men are basically good then why is it so hard to do what's right? Shouldn't it be much easier, why the constant fight? Is it truly about mans intentions? Or are there conditions? Is man good because of what he has never been? Or as good as he can hide his sin? The truth is; the heart of man is as dark as night. That's why there's such a struggle to do what's right. Human nature tells us what to do, and we follow without ever thinking it through. This is why we need to adopt God's nature, we can only do this by becoming a brand new creature. Where has your nature gotten you on your own? How long before your cover is blown?