The Reckoning was founded by Derek Campbell, who grew up in a compound of sovereign citizens in rural Oregon. The compound was attacked by a Beast after they inadvertently stole a mysterious egg from her; it was destroyed, with heavy loss of life, by the Hero who came to "save" them from the Beast
Campbell teaches that Beasts are part of God's plan for the End of Days; their actions might be vile, but they are acting in accordance with their natures and divine will. The Reckoning accepts that Beasts terrorize humans to teach a lesson, or possibly to punish sinners, and they don't actively target them as other hunters would.
Heroes, to these hunters, are far worse than Beasts, not only because they are interfering with God's plan but because their single-minded focus on destroying Beasts results in too much collateral damage. The Reckoning monitors Beasts in order to learn more about Heroes and how to effectively fight them.
Some members of the Reckoning have been personally victimized by Heroes, perhaps the mortal family of a Beast or simply someone caught in the crossfire. Of course, because of their close interactions with Beasts, a number of Reckoning members have become Heroes, but they are often able to conceal this by claiming they had no choice but to kill a Beast for the greater good of the compact.