How do you prove your religion/holy books were not corrupted.

[Angrboda]

How do you know it's not corrupted now, and in the future, a new Messenger will come with a revelation that teaches the will of God?

It not how much light we are granted, but how we respond to the light we have been given. A pure heart will receive true revelation in whatever form it takes, while a corrupted heart will twist even the most pure message.

The Kalamas of Kesaputta ask for guidance from the Buddha

The Kalamas who were inhabitants of Kesaputta sitting on one side said to the Blessed One: "There are some monks and brahmins, venerable sir, who visit Kesaputta. They expound and explain only their own doctrines; the doctrines of others they despise, revile, and pull to pieces. Some other monks and brahmins too, venerable sir, come to Kesaputta. They also expound and explain only their own doctrines; the doctrines of others they despise, revile, and pull to pieces. Venerable sir, there is doubt, there is uncertainty in us concerning them. Which of these reverend monks and brahmins spoke the truth and which falsehood?"

—

Ain't it funny how it's always "those other guys" who are doing the twisting. If you are truly this naive, Chad, then God help you.