Even apostle Peter himself thinks that there are some writings that are difficult to understand. What are yours?
II Peter 1: 15Consider also that our Lord’s patience brings salvation, just as our beloved brother Paul also wrote you with the wisdom God gave him. 16 He writes this way in all his letters, speaking in them about such matters. Some parts of his letters are hard to understand, which ignorant and unstable people distort, as they do the rest of the Scriptures, to their own destruction.
The Bible is deep, not easy to understand.
If some one says I understand the bible fully , that may be the problem.