One observation from being an "observant Jew" for many years:
People who one would think are big believers in ה' א-להי ישראל are actually very small believers.
People who one would think are very small believers actually believe a lot more than we think.
Belief is not a simple matter. R' Yechezkel Levenstein said that he worked on Emunah for 40 years and if he skips ONE day of working on Emunah he feels a weaking. So if you are not working on it daily, expect yourself to fall - even w/o necessarily realizing it.
