If there’s no ultimate justice, what’s the argument against just doing whatever you can get away with in this life? You won’t need to answer for it to anybody.
Don’t people already do that? I think it has more to do with the person and how God created him, than the potential for punishment.
Would you go out and commit murder and rape if it wasn’t illegal?
The argument for not doing just whatever you want and can get away with is that it is irrational. If you want to live the life proper to a human being then you don’t follow every whim and irrational goal that pops into your head or gives you momentary pleasure. You have to use reason to guide your actions and think long term. A rational person doesn’t need to be threatened with hell and damnation to do the right thing. Of course rationality is a choice and many do choose to be irrational. Religion in my opinion is one of the root causes of this because it preaches that man is evil by nature and his mind in not capable of a rational morality. The reason there is so much evil in the world is that people are not taught to think but to “feel” and no one can deny that subjectivism in all its forms is the ruling philosophy today.