When religious talk about life’s purpose, it invariably revolves around what god wants.
But such a purpose seems to me no different than what the state wants from increased population, what your parents want from having a kid, or even what nature itself wants in a link in the food chain. As such, while information of an external purpose can perhaps be exploited for your own personal gain (eg. sucking up to god for some positive divine intervention), there really is no rational reason for it to be your end goal.
Therefore, the question of life’s purpose is a red herring designed to lead people into religion, because the purpose of life can be absolutely anything that other people, animals, machines (or god(s)) want from your existence thus putting god on the top of the list (which would have worked had god actually existed, but even then we must assume that god’s creator is bigger than god and thus his purpose should be priority, but then go’s god’s god’s purpose is even bigger and has priority, etc), but the real question to ask is what you want for yourself: Case, a bacteria in a petri-dish doesn’t care about the biology class studying it, it merely consumes and reproduces as is its evolutionary nature. We may be more convoluted than bacteria, but at the core of our being is still a guiding mechanism that is the result of millions of years of evolution and elimination, and we will continue to do what we do with or without divine purpose, or indeed any other form of external meaning.
It’s funny, because when you measure people up to any religious purpose, you will find that we are very, very ill equipped for it. The Koran predicts a holy war on the sacred lands, but the world – including Arabs – are inching their way towards peace. The Judeo-Christian god demands mindless worship and abandonment of rational reason, but due to human being’s very nature of preferring to not be the ego drones of unproven supernatural entities, we are moving away from that as well. Buddhism suggests we end suffering, and while that is all good and well for an intermediate consequence of many of people’s actions, positing it as the end purpose is still very much arbitrary, providing no justifications and no incentives other than an unproven and frankly unfair karma system.
It is clear, that we are not purpose built machines, for we have ourselves built machines that best us at everything except for “being human”. I don’t know about you, but being brought to this world as a tool for some whiny god’s purpose and then being heavily inefficient at that, does not quite make me feel all that warm and fuzzy. Somehow knowing that I was created to be loved by a god doesn’t come across as much as majestic and glorious as it does creepy.
I understand why some people view a purpose of life as necessary, but external purpose does not give me motivation, and it shouldn’t. For motivation, any of your short term* intermediate goals would work out just fine, and you can take comfort in knowing that without specifically targeting the goal of any 3rd party, you might just be fulfilling their purposes as well.
*short term = within your life time