Which fallacy is committed in the following statement: 'God exists since it is written in the scriptures. Since the scriptures are the words of God, whatever is written in them is true.'?

The argument proves God's existence from scripture, then guarantees scripture by calling it the word of God.

Each claim rests on the other, so the reasoning turns in a closed circle.

The truth of the conclusion is quietly assumed among the premises.

An argument that presupposes what it sets out to prove commits this fallacy.

This is begging the question, or circular reasoning.