"Evil" is relative. By the standards of the Andrastean nations of Thedas, she is unquestionably good. She is actively working to return the Maker to this world.
Except that she's willing to commit acts that are decried as being evil or morally bankrupt by her superiors.
By setting up Hawke to escort Saarebas into the path of Arvaraad, her goal was for Hawke to die and use this as proof of Qunari barbarism against someone attempting an act of mercy. Her plan was to turn Hawke into a martyr to spread hatred against the Qunari.
Furthermore, Ser Varnell kidnaps and murders a contingent of Qunari soldiers, having been radiacalised by her. When she sends Hawke to deal with them, she calls him out, but Hawke can express the belief that Petrice probably ordered Varnell to do it and she was trying to cover her own arse by decrying him. She probably planned for Hawke to killed by Varnell's mob.
Finally, she has the "heretic" Saemus killed to make it appear as if he attempted to leave the Qun and was murdered by the Qunari for it. If Hawke has been against her, she furthermore attempts to make it appear as if it was Hawke who was the guilty party who murdered him.
So, we have numerous accounts of conspiracy to murder, conspiracy to incite religious hatred, two accounts of kidnapping, the murder of Saemus Dumar and attempted frameup of Hawke, all of which we can set forth as evidence in the list of charges against her.
Yeah, whether if she believes she's doing the Maker's work or not, she's a religious fanatic and 100% evil.