While Judaism was never a proselytizing religion, contenting itself with born adherents (and as Thomas Paine wrote in The Age of Reason, "The Jews made no converts; they butchered all." The editor), Christianity was a significant departure from the culture that spawned it, a faith built from converts. This created a foundational need to convince others, or at least intimidate them into acceptance. Thus, the discipline of apologetics is as old as Christianity itself, and comprises a significant part of the religion.
Apologetics is an interesting word. Semantically it suggests an apology, and skeptics would hasten to point out that apologetics was necessary only because there was so much to apologize for! And no one was more apologetic than Paul.
Paul, though not the originator, was the principal founder of Christianity as a religion. It was he who composed an entire theology incorporating doctrines that Jesus, or the anonymous authors of the Gospels, never mentioned. These came to supersede the simple homiletics of the obscure itinerant rabbi, and transformed what was a Jewish reform sect into a new, and increasingly Gentile, religion. When people think of Christianity, it is primarily Paulism they have in mind.
Paul's epistles predate the written Gospels. Their purpose was to build and sustain a Church, and one of their most prominent aspects was their apologetic content. Paul used every means at his disposal to convince others of the validity of his doctrines. He invoked the authority of the soon-to-be "Old Testament," making abundant references to support his arguments. He claimed that "[w]hatsoever things were written aforetime were written for our learning" (Romans 15:4), rendering it into a precursor and prologue to his theology. And lest anyone dispute their value, he and his successors need only insist that "[a]ll Scripture is given by inspiration of God" (2 Tim. 3:16). That these Scriptures had been subjected to severe abuse in their interpretation was a problem that could only be paved over with guile.
In Paul's apologetics, he cleverly anticipated and headed off any objections or reservations that waverers might have; and once netted, sought to keep them that way. Paul's arguments have been the staple of proselytizers for two millennia now. Although the illogic of these arguments is apparent to the rational, they become more and more effective and compelling, the deeper one succumbs to the Christian line. In combination they make Christianity into a virtually escape-proof mental trap.
First and foremost is the heavy emphasis on faith, as in Romans 1:17 & 4:5. Jesus hardly stressed faith at all, but it was Paul's primary mantra. Now why God would insist that we believe a particular quizzical story in the complete absence of proof and which violates our gift from God of innate reason, and make that the fundamental test of our existence, defies all explanation. The impossibility of proof provides the answer, since faith makes the tricky matter of proof seemingly irrelevant. And to require proof would evidence a lack of faith, thus placing one in imminent peril.
When propagating a religion where proof is not available, one that contains logical absurdities, it is essential that the logical processes of the mind be short-circuited. Paul attempted this with his facile quips, "The wisdom of the world is foolishness with God." (I Cor. 3:19), and "The foolishness of God is wiser than men." (I Cor. 1:25). This summarily rejects all logical quandaries as if they're of no consequence, and saves the trouble of having to explain them away. We are merely to trust that, as I Cor. 2:14 informs us, "But the natural man receiveth not the things of the spirit of God: for they are foolishness unto him: neither can he know them, for they are spiritually discerned." In other words, you're incapable of understanding the "truth" of their doctrines because you're working with a sinful, carnal mind, rather than a spiritual one. Once you give up and give in, then you'll understand. This inverts the process of knowing from "see it to believe it" to "believe it, then you'll see it." But should one expect to gain real knowledge subsequently, Paul crushes that by informing us "his ways [are] past finding out!" (Romans 11:33) So don't even try--just comply.
This might be followed up with the familiar saying of Jesus to Thomas "Blessed are they who have not seen, and yet have believed." (John 20:29) Doubting Thomas is such a useful negative role model that if he hadn't existed, it would have been smart to invent him. And perhaps they did. The Synoptic Gospels don't report this episode, only John does. Mark 16:14 implies that Thomas had been present with the others, but John (20:19, 24) says he was not.
Romans 8:6-8 further articulates Paul's strong bias against the sense one was born with. It claims that the carnal is inherently anti-God, which is strange since one would assume God made it that way. It also states that those "in the flesh cannot please God" and "to be carnally-minded is death." You can't get any more emphatic than that.
For anyone not gulled by this tactic and who persists in defiance, a proselytizer might invoke II Thess. 2:10-12, in which Paul claims that "God will send them strong delusion, that they should believe a lie." This section is often used to suggest that textual problems could look cut and dried to you, but only because God made it look that way as punishment for your willful refusal to believe. Certainly it would be within God's power to so confound your mind. (Skeptics should correlate this dastardly measure with Hebrews 6:18, which states that it is impossible for God to lie.) Anyone in this position is clearly at the brink of doom, and had better relent now!
Another coercive tactic of Christian proselytizers is invoking the "unforgivable sin" of Mark 3:28-29. Jesus was vague about this, but to later exegetes it meant resisting the work of the Holy Spirit in his efforts to save your soul. This, of course, is manifested by the proselytizers trying to convert you, so to oppose them is neatly construed as opposing the Holy Spirit, and becomes, by extension, unforgivable.
Backing up all these tactics, of course, is the Ultimate Stick: the threat of Hell Fire. Countless millions have gone along with Christianity merely as a form of "fire insurance." Better safe than sorry, which may be intellectual cowardice, but what a safe, and what a sorry.
Once sucked into the parallel universe of Christianity, the adherent is too intimidated by the existing framework of threats and rationalizations to attempt escape. Even thinking along alternative lines will induce severe feelings of guilt. And should one run the risk of losing faith by examining its true foundations, he is certain to be chilled by the dictum, in Hebrews 6:4-6, that "It is impossible for those who were once enlightened...if they fall away, to renew them again..." Those who originated a religion based on deception and delusion clearly knew that if the conditioning broke down or wore off, it could not work again. But that's when the true enlightenment occurs.
The conversation techniques of Christianity are crafted with a powerful psychological insinuation. Once roped in, people tend to stay in, since every passageway out has been systematically sealed. It is much easier, therefore, to inoculate people against Christianity in advance, using well-developed educational efforts all grounded in our innate God-given reason, rather than attempt to extract them once they've already succumbed. Deists and other freethinking activists should be making a special effort to reach those still perched on the fence, the lukewarm rather than the firebrands. However, reason-based Deism does have the power to reach people who are so indoctrinated with Christianity that they are members of the clergy, as is evident in our "Why Deism?" section.