What about other religions? Islam and Judaism come to mind, but there are also non-abrahamic religions that advocate faith, hope and love. Why is are you exclusively a Christian and not a Muslim, a Jew, a Buddhist or a Pagan? Why are you a Catholic instead of a Protestant? If you were born in China in the early 20th century, would you be a Catholic? If so, why? If not, why are you a Catholic here and now?
Because the Catholic Faith is true. But this is getting off topic.
Occam’s razor is not conclusive and it’s not science. It is not unscientific but I would say that it fits into the category of philosophy. In science you do not get two theories, take the facts you know, and then conclude based on the simplest theory. If you’re doing this, you need to do better experiments to determine the facts. Occam’s razor can be a useful heuristic to suggest what experiments should be done. Just like mathematical elegance, Occam’s razor suggests that something is on the right track but it is not decisive. To look back at the facts and then interpret it through Occam’s razor is just an exercise in hindsight bias.
Your analogy with Norse tribesfolk reminds me of the NRA slogan, “Guns don’t kill people, people kill people”. There are many different levels of causation. The gun can be said to be the secondary cause of why someone died. The person pulling the trigger would be the primary cause. The secondary cause of thunder is nature but the first cause that brought things into existence and created the system is God. Nature cannot be its own cause.
The rest of what you wrote sounds like you’re pulling numbers out of your arse. The last sentence should be read in your best Norse tribesfolk accent.