Although their idea may be well-intentioned, their methods decidedly aren't. Revenant's ultimate goal is to dismantle society's power structures and reclaim in themselves, which may or may not make them a malevolent organization. However, they are not afraid to use biological weapons to achieve this goal, including the Colony operation.
Colony involved spreading a non-lethal virus in Glasgow, Scotland, intending to sicken most of the population so that Revenant could step in as the governing figures amidst the panic. With vaccines in their posession
They would also have vaccines ready to cure people of the virus. The Colony operation was going to happen in 2005, but Cathedral agent Kate Drew stopped it on July 14 by securing the formula and putting the scientist in charge of creating it in hiding (he had been threatened by Revenant). Before she could get away, though, Kate was killed in a car wreck.
In 2013, Nancy is sent a letter from Cathedral saying that the Colony operation is restarting and that Glasgow needs her help, but it turns out to be a letter sent from Revenant to lure her to Scotland and find the scientist and the formula. Revenant continually hacks her phone, giving her messages from Kate if she helps them, and taunting her and the population with things like an envelope with a note that says "July 14: Save the date!". Nancy eventually finds out that a Cathedral operative, Ewan Macleod, is actually helping Revenant, as he steals the formula from Nancy once she finds it. Combined with the scientist's information which Revenant was able to track down after listening in on Nancy's call to him, they are able to make four bombs containing the virus. However, Nancy disarms them and the operation is stopped once again.