What is the best of Faith?

Most of unfaithful people are ready to Question about anything even which have the proof of the success.

Ref.: Confirmed from experience of staying in Kuwait, after first time coming to Kuwait.
(before my world was this much Small)

(“Respect” is “Good Manner”, a part of Faith.
Better Faith is “LAILAHA IL-ALLAH”;
What is the best of the Faith?)