This is a great question, often asked by teenagers to frustrated parents or some other authority figure. However most of us have asked this question at one time or another. Sad to say most Christians aren’t prepared to give an answer, and if anybody has an answer it should be us. In the 1640s this question was posed in a different way in the Westminster Shorter Catechism, Question 1.What is the chief end of man? And the answer is beautifully simple, as most things from God are. The answer is: Man's chief end is to glorify God, and to enjoy him forever.
That is the purpose for which God created us, to glorify Him and enjoy Him. This is the reason for the God shaped hole in our being. We are destined to fill it with Him. I think the reason most Christians can’t answer it today is that we have become so caught up in denominational infighting we have forgotten that search. We can’t answer a seeker when they ask this question. So we fill them up, or try to, with doctrine and tradition. When the whole time the simple answer is to glorify God and enjoy him.
Imagine if we went into the world with the message to seekers that there is a point to this life. That’s why the idea of nothingness is unsatisfying, and so is the idea of doing it yourself (those two pretty much sum up all religion or no religion). God built us to have a relationship with him, not for a bunch of stale rituals. The message is you have a point; you have a beautiful and wonderful destiny. You were created by God and given gifts from him so that you can glorify Him and enjoy Him.
Not all Christians study Catechisms. Mostly because they mistakenly believe that it is only for a specific denomination, but it would do us all good to remember all truth comes from God, no matter who says it.
So remember Why am I here or What is the chief end of man? To glorify God and to enjoy Him forever.