God: "I looked for someone to take a stand for me, and stand in the gap" (Ezekiel 22:30)
None have assurance at all times. As in a walk that is shaded with trees and chequered with light and shadow, some tracks and paths in it are dark and others are sunshine. Such is usually the life of the most assured Christian.
All false religion is based on works to achieve God’s favor. And when you base it on works you will either use God’s Word as a means to obtain God’s favor or ignore God Word and create your own expectations. Both are deadly because both short-circuit God method of grace.