Im looking for spiritual verses, religious text and quotes that concern the Emperor and how he is described to the masses in the Imperial Creed.

I recently watched Ressurection, a 1999 thriller/mystery film with a religious tilt to the serial killer, and this movie, along with Seven, have me interested in putting together a heretical plot of an insane fallen priest attempting to recreate the Emperor, but in truth is unwittingly creating a Daemonhost.

So I was thinking of some components that make up the Emperor.

Noble Blood. Warrior's Heart. Broken Body. Warp Seeing Eyes. ETC ETC

But Id like to have these in verse and the more official 40K references the better.

Im not sure exactly what the overall arc is, Im leaning toward the victim's being all connected (a former acolyte cell who were once involved in the banishing of a daemon, perhaps Marabas or The Horned Darkness) and the fallen Priest was also one of them. He is on a holy quest to renew the Emperor and has the Emperor's Blessing (which is, unknown to him, actually a Dark Pact with a daemon).

Im not sure if the PCs will be active acolytes/agents or just get involved in a more of a call of cthulhu manner, but am leaning toward their Inquisitor beign the same Inquisitor that presided over the former acolyte cell and thus sends in his rookies to help with the investigation of the murder of one of his former pupils, though he will not openly state that.

Libation to the Emperor
The Emperor is our guiding light,
A beacon of hope for humanity in a galaxy of darkness
As we serve him,
He is our greatest servent
As we pray to Him,
His thoughts are only for us
And in the dark when the shadows threaten,
The Emperor is with us,
In Spirit and in fact

Prayer of Adulation to the Emperor
(To be recited every morning)
O Immortal Emperor: have mercy upon us, miserable unworthies that we are
O Master of the Galaxy: protect your flock from the alien
O Keep of the Light: Guide our darkened path with your radiance

We are your warriors and we are your servants to thee,
We stand free from blindness of heart,
Free from hypocrisy, vainglory and deceits,
But captive to hatred, malice and anger
To the filth, the alien, the heretic.

By thy agony and bloody sweat: by thy golden throne and thy death,
By thy destruction and re-emergence as the god of men,
Keep and strengthen us, we who fight for thee

They're from the Imperial Infantrymans Uplifting Primer, there's a (fair) few others but those I thought where both pertinent. The second in particular should be stamped into the brains of fairly much anyone from an Imperial World, Schola Progenium or from an Imp Guard background. Most of the other prayers are fairly similar.

There are also dozens of litanies for everything from stopping your arse being blown up by bombardment, staunching wounds, unjamming your lasgun and hoping your krak missile blows the f*ck out of what your shooting with it.

While some players might think it sacrilegous to do so, the following might the best approach:

You could very easily take verses out of the bible, changing what you need to like references to god becoming the god-emperor?

For creating a plot like that which is actually a very Thorian thing to do (if you've read the Ascension Thorian Section), resurrecting the emperor in a new "vessel" that the Thorian Inquisitors search for is an actual thing so your plot is easily thinkable, so you could consider the "vessels" that are "worthy/strong" enough to hold the emperors essence and bring it in that way and just have it so that a daemon learns of the plans of the guy trying to bring back/recreate the emperor and takes over the vessel and maybe acting as the Emperor himself?

For religious texts, in an Empire the size of the Imperium, making your own wouldn't be too far a leap from the libraries of hymnals and written texts of devotion that fill the Imperium and gather dust as new ones are written up.