The best argument is that the physical cannot create itself from nothingness. So,
there must be something more fundamental than the physical. So, one could argue if there was no fundamental agency nothing would be here.
So without some fundamental agency there would be nothing. But there is...
I think you need to tell us what version of Christianity you are representing. There are very conservative to very liberal interpretations out there. What are the basic tenets you are representing?
Stating the obvious,
I am not a Christian even but expressing my very considered opinion that I consider fair, informed and unbiased even if you don't, Mr. Grouch. I have no motive to bias things for any conclusion.
Oral testimonies passed down from his life and maybe lost even written testimonies are still very important to consider.
My overall assessment is that much of the gospels is true events and teachings, but with interpretation and author's intent as things that have to be considered also.
My thought is that you can be a Christian and have a more evolved understanding of God than the Old Testament shows at certain points. Actually, I believe Jesus' mission was to bring a better understanding of a loving God.
Not necessarily as ancients probably did not believe in man's evolution or even that the earth was round. I do believe in the afterlife from modern Afterlife Evidence.
You have a common misconception that I once had. The Immaculate Conception is not about Jesus' birth as I had thought.
Immaculate Conception - Wikipedia
The Immaculate Conception is the belief that the Virgin Mary was free of original sin from the moment of her conception.
I listen to channeled sources that 'get out of the way' and don't have conscious memories of what happened in the trance. I call that possession.
I think many ancient cultures that have barely survived into the modern age make use of possession as part of their ceremonies.
I would have once...
I might sometimes take the position 'I believe something is highly likely to be the case'. While it seems your position in all such cases would always be 'I'm not guessing'.
Action based on reason and best chances is a positive trait of rational beings.
In the face of an unknown some stances can be rationally more believable than others.
You are trying to say explanations for all things not provable are equally likely. I’m going to disagree with an example like aliens are more likely than the Easter Bunny although both are not proven.