It is not only possible, but common practice to ignore religion when going for domination.
On high difficulty levels, getting a religion of your own can be a very expensive investment, only done for religious victory. (on Deity, you usually have until about turn 50 to get yourself a prophet. Building holy sites and doing holy site prayers sets you back a lot in your expansion phase)
If you are relatively successful with your domination, you generally don't need to even think about it at all. The AI simply won't win earlier than you do. Even on deity, i don't think the AI is ever likely to achieve any VC before turn 200.
If you are a bit slow on your conquests and it seems the AI might be able to compete for another victory condition before you win you could do some of these things:
-Attack the strongest civ's first.
-Probably only possible in early game: ally some civ's make them fight with others. War slows down their progress. They also can't very well convert cities from civs they are at war with.
-Use the world council to get stuff happen that slows down the AI that may be a threat to achieve victory or simply the strongest
-Be at war with a civ that threathens to win by religion so that your military units can keep their religious units out of your country. (If you are already converted, maybe you can try get a competing religion to come convert you by not being at war with them)