Well, I think I have a few interesting points.
Most of what has been said here and corraborated about the meaning of life has been the example of a humanist lifestyle. Humanists just want to further the race and help those around them without any more motivation than that. Before I became a christian, I thought of a scenario that solves the humanist problem but in a non-humanist way. This is in no way a reason to believe, but is interesting to ponder. If everyone in the world was a real christian, then we would have a perfect humanist world. If everyone lived following Jesus's example and loved God, then we'd all be doing our best to help one another.
The hardest part of proving any theory of life is to look at creation. It's up to each of us to figure out what we think of it, but how far can science go to help us understand where we came from? If life is a random chance, then why do we or even any matter exist at all? If you remember back to high school, you'd probably heard about all those debates between biogenesis and abiogenesis (I think those were the terms). When we look all the way back, we must have come from nothing at one point. Where did something come from nothing? That's where we all place our bets.
When we all look at our lives, we can see that we've all made our mistakes. Even the best of us can't count the times they've hurt others on both hands. If life is about helping each other, then we'll have one tough time convincing others. If you're looking into pleasure as the meaning of life, then why can all these 'pleasurable' things (eating, drinking, sleeping, sex) end our lives so easily? That's a paradox that I think denounces that way of thinking.
And lastly, I always want to differentiate between christians and catholics. Don't blame all christians for what some catholics believed in. If there were more leaders than followers, we wouldn't have so many types of christianity and past atrocities. What Christians live for is the love of God and their trust of Jesus. They don't justify themselves with their deeds. In truth, all men should be leaders.
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