There is a world where gods exist—but they are just mighty beings. Not almighty and surely not omnipotent. However, far beyond any capabilities of any mortal beings (they're gods after all). Gods, however, can not directly manipulate mortal minds unless those mortals are in high faith with them.

There are "good" and "evil" gods, but the concept of "good" and "evil" exist only in the minds of mortals. Now, because they are gods, they will generally try to shape the mortal world according to what they are. Gods who prefer wars will try to create more wars, gods who enjoy pure nature will grow forests etc...

There's an "evil" god Y who is inherently "evil"—requiring sacrifices, demanding slaughtering any who don't believe in Y, etc. One of the thing Y finds most amusing is imposing itself to some others and shaping them to its "faith", i.e. following "evil deeds".

This Y laid eyes on the race C of beings who are perceived by mortals as "very, very good beings" and Y wants to convert them. So Y imposes itself on them, wishing to convert them to do evil deeds.

**How can the people of race C remain "good" under any pressure Y can do on them**? 

*Remember, Y can not just simply convert their minds because initially they do not believe in Y (as it is an "evil" god). But Y can do advanced trickery, threats and so on and use full arsenal of it superpowers.*

*Also, Y doesn't want to exterminate race C but is fine with killing some of them to "make an example." Race C are mortals so they will be generally afraid of superpowers of the god and the miracles ("good" or "evil") it can bring*

(for the sake of personal preference - one can swap "good" and "evil" in the question and the meaning will remain same)