Pentecost is called the "Birtday of the Church" because it marks the start of the mission of the church. It is when the Apostles went out to to spread the teachings and message of Jesus, which then established the beginning of the church.
God is an unfathomable being and so is ourselves. Science did not explain the things how we are able to stand here today and we are too ignorant about using our rationality in learning about ourselves. Even though, many who believe in God are said to be only blinded by faith which is not something you can see because how could you even explain someone or something has this most power of all held by a divine being and he was the only one who rules all of us. Human beings are too unstable to realize the truth of the world and only held ignorance in living. So how could you not say that we do not have God who is the basis of creation? Imagine being born in this world without a creator or a purpose for that matter. There is God, there are many scriptures written about him and words has been made flesh which is Jesus Christ who died for all of us.