To be critical

To be critical, you must always need to have these 7 ideas in your head. While the note was more towards history/sociology/psychology areas, you can always extend it to everything else, including religion.

Ibn Khaldun starts the Muqaddimah with a thorough criticism of the mistakes regularly committed by his fellow historians and the difficulties which await the historian in his work. He notes seven critical issues:

"All records, by their very nature, are liable to error...
1. ...Partisanship towards a creed or opinion...

2. ...Over-confidence in one's sources...

3. ...The failure to understand what is intended...

4. ...A mistaken belief in the truth...

5. ...The inability to place an event in its real context

6. ...The common desire to gain favor of those of high ranks, by praising them, by spreading their fame...

7. ...The most important is the ignorance of the laws governing the transformation of human society."

He really had a lot of interesting ideas that are worth exploring.

https://en.wikipedia.org/wiki/Muqaddimah