1 Corinthians 14:33
"for Yahweh is not
a Elohim of confusion, but of peace..."
Romans 1:20-21
"20 For since the creation of the world Yahweh’s invisible qualities—his eternal power and heavenly nature—have been clearly seen, being understood from what has been made, so that people are without excuse. 21 For although they knew Elohim, they neither glorified him as Elohim nor gave thanks to him, but their thinking became futile and their foolish hearts were darkened."
The Bible contains the factual information about Yahweh, and His Son, the history of His people, and just some of the plans he has for this earth and in those plans are contained the fact that Yahweh will rule through Yahshua the Messiah over this world at the end of the age of man. It's not simply an unverified assumption to believe in Yahweh. Yahweh's majestic power has been revealed through His works, the beauty and immense love that He put in creation and most of all, His most precious works of His majestic creative power, Him sending His only begotten Son for our sakes so we could receive forgiveness for our sins and walk in newness of life worthy of saints so we can attain to a level of perfection pleasing to the Father and rule and be with Yahshua in the Kingdom.
Assuming that Yahweh does not exist is indeed in my opinion the most incredibly nonsensical thing a person can do.