If you knew for sure, for SURE, that life on earth was an experience that lasts from birth to death but is in no way the beginning or the end of you, behavior would shift to benefit the spirit instead of the physical. And vice versa. And these are not necessarily divergent behaviors but certainly can be and are in many cases.
Want proof one way or the other? Ask for it. Out loud. Start with Dear God I ask ..., end with ... I Ask this in the name of Lord Jesus Christ. As simple as that. Loud, clear, specific, short and simple.
The answer is the premise by which you live a lifetime after all. I think you can afford to do what potentially may seem foolish.
There are plenty that have already made up their minds one way or another. But if you are not sure, ask. Don't expect a voice to come forth. But do expect an answer. A personalized answer in a way that only you will recognize. In fact, ask for the knowledge, to know once and for all. Think about it hard so that the knowledge one way or the other comes to you, by whatever way necessary, be it logic, a miracle, a sign only you would recognize, or whatever way it comes about. But don't rely on your past preconceptions if you currently don't KNOW.
After all, it is purported "ask and you shall receive", you've heard that before I'm sure. Ask OUT LOUD. You don't ask others by thinking it, so speak up.
I am a man of science with no religion. No faith. No belief. A very intelligent man. I man of knowledge. Yes, I know.
Sure you can ask me what I know, but it won't matter to you what I say unless you trust me more than you.
Report back what you KNOW only if you previously did not KNOW and now do KNOW after this simple exercise.
Would the answer change the way you are living? If not, then carry on. If so, don't you think it would be prudent to find out, or at least put a slight effort towards finding out? Today.