Auresius

First of all, the question (Q1) "why would God exist?" in my opinion is really just a reformulation of (Q2) "is there a reason/need for the actualisation of the concept of God?", which I believe is the essence of your question. After all, when you ask "why?" you expect to be answered with "reasons for why". If after careful consideration you decide to answer Q1/Q2 with "there is no reason/need for the actualisation of the concept of God", then you will inevitably be led to answer another question (Q3) "does God exist?" with "no" or with a modest "most likely not", for the simple reason that a superfluous God that fulfills no need and no reason is a self-contradictory self-refuting concept (a useless God is no God by definition). This logical connection is why I am more or less equivocating your question (Q1) with my own (Q3). As to your challenge, I think if i were to make a case for why God would exist it would most likely be a reiteration of classical arguments that you may already be extensively familiar with. (some of which I mentioned in a previous post) I would be surprised if they haven't been brought up and dealt with in great detail in these forums before this time...? I'll be submitting one argument at a time if that's where you see your thread going. (sorry, a little bit short on time right now)

Thanks for your answer. I have to say that I disagree with your comment. I am myself religious and I do not think that no one ever argues substantially for or against the existence for God, whether they're religious, atheist or otherwise. Perhaps I have provided in my previous post an example of how a religious person can fully entertain the possibility of there being no God. Perhaps that shows that not everyone is dogmatic.

Why would there be a God? I think for there to be a God, there would have to be a necessity for His existence, or the proposition of His nonexistence would have to be plausibly untrue. Several arguments have been developed throughout history to back the idea of the necessity of His existence: cosmological argument, epistemological argument, ontological argument, moral argument, etc. If these classical arguments do not hold in your opinion, then you must conclude that God does not exist or at least is unlikely to exist. Thereby you would have answered the question of "why would He exist?" by "for no reason", which translates to: a God that would exist for no reason is a useless God that is disproved by its triviality.