What is the most effective way to destroy a deity of faith? It's simple, destroy their temple, massacre their followers, and turn them into rootless drifters. As time passes and their divine power is drained, they will naturally perish.
The most direct method is to lead a legion into their divine kingdom, shatter their divine body, and crush their divine kingdom, but this method only treats the symptom, not the root cause.
As long as their church remains and their followers are alive, given time, they can resurrect. Therefore, eradicating a deity through brute force has a very low cost-performance ratio.
The best way is to intimidate the deity into hiding within their divine kingdom, then dispatch a legion to destroy their temple and slaughter their followers. This is what Tiffany, leading the giant legion, was doing at the moment.