The Lectitio Divinitatus
Like many of the Mechanicum, the Tech-priestess Verity proclaimed the Emperor as divine, the Machine-God Omnissiah, the instant he set foot on Mars. Similar beliefs were not uncommon among those conquered by the Imperial forces during the Great Crusade and even the Terran Wars of Unification.
The glory of the Emperor - his power and majesty, his psychic potency and charisma, not to mention the military might of his forces - seemed godlike to those he subjugated. So complete, so total and so swift was their defeat it was as if an angry god had conquered them. The fact he toppled icons and temples, decrying these images as false and demanding the people worship them no longer, did nothing to challenge that presumption.
It availed little for the Emperor to preach the atheistic Imperial Truth and to order no religion, no worship, no superstition; faith is endemic to the human condition and in the shattered footsteps of the Great Crusade's wake, cults sprang up venerating the Emperor and his myriad court of Primarchs, Custodians and Astartes as divine.
Within that court itself, of course, there was no public worship. Between the Master of Mankind and the Lords of Mars there was an understanding, a spiritual détente; he would not publically condemn their adoration, they would practice their rituals in secret and neither proselytize nor challenge the Imperial Truth. Some of the Imperial Army might have been men of faith - either worshipping the Emperor or clinging to some more primitive tradition - but if there were they wisely kept their beliefs hidden.
Among the Custodians and Astartes, of course, there was not even a hint of such superstition. Supremely loyal to the Emperor, they were not awed by him as normal humans were. They understood the things - weapons, vehicles, armor, even their augmented selves - that appeared supernatural to the common folk. Genetically descended from him, they knew he was but a man. The supreme man, the paragon of humanity - but a man nevertheless.
And so it was all the more strange when the Emperor's seventeenth son bent the knee to him not as a father, but as a god.
The planet of Colchis was a world ruled by an ancient religion known as the Covenant and the Primarch Lorgar, after being thrown to that world by the disrupting powers of Chaos, had risen high within its priesthood. Assailed by visions of a mighty warrior in golden armor, Lorgar soon came to believe this was the one true god and that the gods of the Covenant were at best subordinate to him and, at worst, false idols to be cast down. The masters of the Covenant could not permit this heresy to go unchallenged.
And so a holy war erupted on Colchis, engulfing the planet and forcing the whole population to choose sides. Eventually, Lorgar's "Godsworn" were victorious and those of who refused to convert to his belief in the one true god were put to the sword. Lorgar, now the high-priest of the reformed Covenant, promised his followers the one true god would arrive on the planet within a year and they would know him only as "the Emperor". When the Emperor reached Colchis and he descended from his landing craft with Magus the Red at his side, there was no doubt in Lorgar's mind that he knelt before his god.
But it was not merely the cyclopean Primarch who accompanied the Emperor. With him, all-but-hidden behind the hulking, ornate forms of the Thousand Son's Astartes, was Verity. When Lorgar organized months of festivity and ritual to honor the arrival of the one true god, the Emperor chafed at it, uncomfortable with the adoration shown him and eager to return to the Great Crusade. But Verity embraced it and eagerly flung herself into it - for the first time, one of Emperor's sons, semi-divine beings themselves, recognized their father as a god. Not only that, but Lorgar had developed a profound theology which gave shape and structure to this (to Verity, at least) obvious truth.
Verity participated in the rituals, melding them with her own faith in the Machine Spirit and the Omnissiah, offering incense and prayers to the Emperor of Mankind alongside the people of Colchis. Uninterested in the delicacies offered at the grand feasts in the public squares, she sustained her organic components on fiber cakes and flavorless nutrient broth and sought out the priests of the Covenant, questioning them intently on the most minor details of theology.
Many of the answers they gave did not satisfy her; her unique abilities to sense falsehood meant she was aware when they dissembled or speculated about something they were ignorant of or their theology had never encountered. And she was not shy about letting them know she was aware of their attempts at obfuscation. "All I want is the truth!" she exclaimed in the courtyard of the Cathedral of Illumination. "Is that so hard?"
"Perhaps, metal-maid. Perhaps." Verity turned at the voice - striding across the courtyard was Lorgar himself, a magnificent figure in golden armor and crimson robes. "You demand to understand the ineffable as you understand cogs and circuits. Such a thing is beyond you, beyond even me. If your mind is incapable of grasping it, can the truth truly be said to exist?"
"Knowledge may be divinity," she countered, "but truth is that which comports to reality. To know falsehood is to know nothing, and so the Omnissiah who comprehends all knows only truth. So I say to you; if a thing exists it is true and only the truth exists."
For an instant, Lorgar looked her. And then he laughed. "Withdraw with me, metal-maid. Let us speak of the one you call Omnissiah."
And so began a conversation that never really stopped. They withdrew together to a side chapel of the Cathedral, debating the nature of truth, divinity and the Emperor. When the Emperor and his entourage left Colchis, reuniting Lorgar with his Legion and charging him to prosecute the Great Crusade, they remained in contact through encrypted epistles sent via uncomprehending astropaths.
Who can say who truly influenced who? Verity's faith in the Emperor's divinity was a logical thing, a function of evidence weighed and measured, a religion of facts and conclusions. Lorgar's was more spiritual, a religion of revelation and visions. She saw his supernatural experiences as vindication of her intellect, he saw her cogitation as confirmation his visions were authentic.
The last communication Verity received from Lorgar was a transmission doubly encrypted, so subversive was it. Occluded with vermillion-level encoding and then translated into Mechanicum binharic cant, Verity received it just as the Emperor's expeditionary fleet came out of Warp outside a system in the Segmentum Tempestus to the galactic south of Holy Terra. As the system was scanned and compliance plans formulated, Verity sang the cant to herself in her techno-sanctum. As the fleet fired up its realspace engines and moved towards the center of the system, she translated pulses of ones and zeros, of on and off, into the confusing and emotion-laden letters of organic language. As the fleet breached the Oort cloud and moved into the star's biosphere, she decrypted the jumble of letters into meaning. And as First Captain Sigismund ordered his battle-brothers into the drop pods for planetary assault, she committed the missive to memory.
Even if she were an unaugmented human, with a merely organic brain, she would never have forgotten the words Lorgar had written. As it was, they were recorded in her memory banks as well as burned into her very heart and soul. The book Lorgar had sent to her was a comprehensive treatise on the divinity of the Emperor, effusive and laudatory in its praise and adoration, but dense with precise and penetrating theology. It was an expression not just of his own faith, but the culmination of their long conversation. The book was the Lectitio Divinitatus, Lorgar's masterpiece of faith.
Both Lorgar and Verity knew very well what the Primarch's work represented - a direct challenge to the atheistic Imperial Truth, an affront to the wishes of the very god they lauded. Outside of his most-trusted battle-brothers, Lorgar had shared it with no-one but the Tech-priestess. The time might come when the Lectitio would be shared with others but, for now, it must remain secret.
And so Verity destroyed the scrolls recording the binharic notation, performed a deep memory-wipe on the servitor who had brought them to her and even killed the astropath who had received the message. With the only copy of the Lectitio Divinitatus outside the Word Bearers Legion safely stored in her memory banks, she boarded the landing craft of the second wave, joining Sigismund's forces already fighting an alien army for control of a system Imperial cartographers had named "Ophelia".
It would be her last planetfall before her death and apotheosis.