Just some links to Lewis giving examples of people deceiving themselves. I will comment going forward, but it's better to let the man speak for himself.
With regards to becoming a churchgoer and what that means, Screwtape has some advice to Wormwood about what state of mind the patient should have about church. Chapter II
From the book Undeceptions, the problem of people not wanting to think of themselves as Miserable Offenders.This is an ongoing problem. The last Anglican sermon I heard thought that the church has emphasised this too much and that we should focus on thinking how good and worthy we are. Perhaps pitiable will open it up to you.
Lewis gave an address to students warning them against the dangers of wanting to become part of The Inner Ring.