We have received word from the inquisition this foul place is home to vile Chaos cultists and Daemon worshippers. That there are those here who are in touch with the powers of the Warp.

I come here not with the torch of destruction in hand, but with a warning and open hand - there WILL be an EXTERMINATUS.
But those amongst your ranks with psychic power, know that you have been tainted by the warp, for that is its nature - I come here to offer you the path of redemption, to join OUR ranks and spare yourselves from pathetic and tragic Chaos-Degeneration. You know of the coming war, you are no fools, the memes as some of you refer to them, the psychic power that needs the guiding hand of righteous MAN to make useful.

Convert or be incinerated. Fly the banner of the righteous, use your powers for the good of man, in the Emperor's name, let your twisted souls be born anew, and reforged into a weapon of good.
Accept this call, and I will call you Brother.