God

We are here on earth, because God needs us.

The question 'Why are we here on earth?' can be answered in two steps:
1) First of all we will have to know as to whether there is any God or not;
2) If we can somehow come to know that there is a God, then we can further ask the question as to why he created the universe.

When we will have the answer to this question, we will also come to know as to why the universe exists, why we exist, or why we are here.

The above two have already been answered here1 and here2 respectively.

John Zande, a militant atheist, in a blog post Why? A Challenge to all Believers (December 4, 2015)1 has put this question to all believers:

Why did your God create this universe?

It is not actually necessary that “fine tuning” of certain parameters will have to exist in reality for proving the existence of God. I think light with its very peculiar properties is sufficient for that purpose.

Is There a God?

The question as to whether there is a God or not can only be answered properly when we will be able to settle the matter regarding the age of our universe. Either our universe is infinitely old, in which case we will have to assume that it was always there. Or we will have to assume that it is not so old; rather it began to exist merely 13.8 billion years ago. Scientist Paul Davies in an article “Is the Universe a Free Lunch?” has explained very nicely as to why our universe cannot be infinitely old and that why it should have had a beginning:

In a debate between Dr. William Lane Craig and Quentin Smith on March 22, 1996 Dr. Craig has thus given a theistic notion of God in his opening arguments: "a personal Creator, uncaused, beginningless, changeless, immaterial, timeless, spaceless, enormously powerful, and intelligent."