This poem is really speaking about the absurdity of life. The mention of God is a reference, or a metaphor, to life itself. Laughing in God's face is about standing up to the difficulty of life, no matter what, and seeing the funny side, the humour, in what is ultimately, a very weird experience. So what you are saying is very near to what I was implying, and like you say, the beauty of poetry is to be able to have your own interpretation. That is often a gift also for the poet, when new interpretation are offered. Thanks for reading and commenting.