I beleive if we do have a purpose on this earth, in this lifetime, it is inherently connected to love. Love is possibly the most powerful emotion. When we are able to give and receive love, it becomes exponentially stronger and impacts the world in waves that in turn create more love, that create more love, that create more love, and on and on etc. So what is the purpose of this love? Maybe to overpower hate, to bring humanity to a higher consciousness, to manifest itself until love is all that remains. And God is love, right?
Another aspect to the meaning of life is creation. All animals, including humans, are driven to perpetuate their species and create more of themselves. Humans do this through love. And love in a way has the same drive: to create more of itself and perpetuate love through all time. If God is love, and love's purpose is the creation of more love; then God is recreating himself through love and when humans love they are creating and strengthening God.
Of couse these suppositions like all others beg more questions...
Under these assumptions, if our purpose is to serve and create God by loving oneanother, then what is God's purpose? Or if you prefer a different terminology: If we are here to perpetuate and strengthen love then what is the purpose of an all powerful love, in a cosmic-universal sense?