Of course when we use only our brain the doubts and questions will arise, but for those who have communicated with God on the matter we know the answer even though it may be unacceptable to those who have not. Your question has an answer and you knew it before you asked even though you effectively are wanting to reject it or perhaps to reject the possibility that God had no beginning. That is almost inconceivable to our human mind.
It does not start with knowledge, but with faith. If you doubt that that is a meaningful answer then you need to try to step out in it earnestly from you heart:
"But without faith it is impossible to please him: for he that cometh to God must believe that he is, and that he is a rewarder of them that diligently seek him." Heb 11:6
What is in my heart can only be shared with another, such as yourself, if God is in it, and if you are really willing and your purpose is right. I know that that answer will not satisfy someone to wants to move forward only by his own mind perhaps using something like the scientific method, but wanting it to work that way will not make it so. It is the way it is. The only way to get there is the Way that God has provided. You are allowed of course to go your own way, when your time is finished, then so are you.
"For my thoughts are not your thoughts, neither are your ways my ways, saith the LORD.
For as the heavens are higher than the earth, so are my ways higher than your ways, and my thoughts than your thoughts." Isaiah 55:8-9