God

Some scientists are now saying that the universe is eternal, that it has always existed even before the big bang. Universe in its present form is only 13.8 billion years old, but before that it has existed in some other form. But before the big bang there was no space and no time, because space and time came into existence along with the big bang only. So if the universe was always there even before the big bang, then it was neither in space nor in time, because before the big bang there was no space and no time. Being neither in space nor in time it will thus be spaceless and timeless.

Actually science has already admitted the existence of a spaceless and timeless God on the very same day when science has declared that space and time in our universe are relative. This is because existence of a spaceless and timeless God implies the relativity of space and time. Mystics have repeatedly said about their God that he is spaceless and timeless. So, if there is a God, then there is the presence of an everlasting state of spacelessness and timelessness in addition to our universe, because this God is everlastingly present with all his attributes.

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.