“Belief is the lowest form of religious involvement, and in fact, it often seems to operate with no authentic religious connection whatsoever. The “true believer” –one who has no literal faith, let alone actual experience — embraces a more-or-less codified belief system that appears to act most basically as a fund of immortality symbols. This can be mythic-exoteric religion (e.g. fundamentalist Protestantism, lay Shintoism, pop Hinduism, etc.), rational-scientism, Maoism, civil religion, and so on. What they all have in common, when thus made a matter of “true belief,” is that an ideological nexus is wedded to one’s qualifications for immortality.
I believe this generates a peculiar, secondary psychodynamic: since one’s immortality prospects hang on the veracity of the ideological nexus, the nexus as a whole can be critically examined only with the greatest of difficulty. Thus, when the normal and unavoidable moments of uncertainty or disbelief occur (magic: is this dance really causing rain? mythic: was the world really created in six days? scientistic: what happened before the big bang? etc.), the questioning impulses are not long allowed to remain in the self-system (they are threats to one’s immortality qualifications). As a result, the disbelieving impulse tends to be projected onto others and then attacked “out there” with an obsessive endurance. The true believer is forever on the make, looking for converts and battling disbelievers, for on the one hand, the mere existence of a disbeliever is one token less in the immortality account, and , on the other, if the true believer can persuade others to embrace his ideology, it helps to quiet his own disbelieving impulses. If mythic-religious , he crusades against sinners, burns witches, hangs heretics; if Marxist he lives for the revolution that will crush disbelievers (and in the meantime jails “witches,” psychiatrizes “heretics”); if scientistic, he often begins a concerted diatribe on rival (heretic) worldviews. It is not the rightness of wrongness of the opposing view but the peculiar passion with which it is opposed that belies its origin: what one is trying to convert is one’s own disbelieving self”
— Ken Wilber, A Sociable God
I think this is right on. This especially relates to modern day Christianity as I’ve experience it. Christians who are still entrenched in modern world-view seek so desperately to convert the “lost” but how much of that is to secure themselves from their own doubt?