The DUP was Ian Paisley's party, it always was a Christian Fundamentalist party and always will be. This leadership election was held because Edwin Snoots' predecessor, Arlene Foster, lost the job because she was not fundamentalist enough.
The DUP is in power because more people voted for it than voted for any other of the unionist parties, because they were too liberal in their attitudes.
Posters on GN may not like his religious beliefs, but they are those supported by the party and its voters.
Which ever way you look at it there is going to be a large group of agrieved voters in NI. With the DUP in power the right wing Christian fundamentalists, and there are a lot of them, are happy, but those who want to see a more modern and liberal country, and there are a lot of them as well are not. Reverse the vote and there are a lot of happy moderisers and also a lot of aggrieved Christian Fundamentalists.
For the time being the Christian Fundamenalists get the most votes and are in power. That is what democracy is.