Loaded question, I know. One can view it from many perspectives. But ultimately it comes down to this: Does mankind have a reason for existing? I would argue that the existence of mankind is proof of the existence of a creator.
Can we say that man exists to do good? It leads to a couple more questions…why do good if our earthly existence is so fleeting in the bigger scheme of things, and secondly, what can be defined as good? Ok, I’ve also heard that mankind exists to have fun. But that does not really answer the question, does it? Or maybe it does, in a very superficial way. But what does “fun” or “doing good” or any of those do you when you die? Can you lie back on your deathbed and say I’ve had enough fun, or I’ve done enough good?
But even that is just a rabbit trial, because those reasons can at most be suggestive, but not normative. It cannot say why man must necessarily exist. I fear that materialism is not much help here, since it can only argue that man must exist as the result of chance, a non-enitity with no causal power. Can chance thus be normative? Materialists for the most part argue that mankind won the cosmic lottery, either through sheer luck or through proposing a mutliverse. The multiverse theory, however, still doesn’t answer the question satisfactorily, since it can only speculate that since many universes exist (unproven), then there should necessarily be one in which we exist. But why is that necessarily so? To say that it necessarily so because we are here is to simply beg the question. It also runs into another issue.
According to Dawkins, the universe is an extremely complex place, and he supposes that God must be impossibly complex since only something more complex can create something as complex as the universe. (Not a very good argument, but ok.) Given that, it is impossible for the multiverse theory to work, since it multiplies a similar complexity by however many universes are proposed. Remember, every other universe must be at least as complex as this one to justify the existence of mankind.
Of course one may suggest that we don’t necessarily have to exist, and be done with it. But we do exist, so we necessarily exist.
Getting back to the original question, we still seem no closer to an answer. But we have a clue or two. Doing good implies something bigger, and the necessary fact of our existence does say that we got here somehow. Doing good only makes sense in terms of a personal environment, it is relational by nature. One can hardly do good if there is no do-gooder or good-receiver. And mankind coming into existence to do good then also has to be personal in nature, leading us to a personal cause, or creator. Because doing good doesn’t necessarily make sense if we are just a fleeting spark of earthly existence.
I guess we could have shortened this long ramble if we had just read the shorter WCF:
What is the chief end of man? Man’s chief end is to glorify God and enjoy Him forever.
That is how we got here and why we necessarily exist. We glorify God by existing, and we do good because we share in God’s grace. And we have great joy in Him. It can be no other way.