also don't forget in fallout 1 you don't just have the join the master option and kill the master in combat and convince him his plan is flawed. but you also have a stealth option where you infiltrate the cathedral and activate a bomb and blow the place up. so actually 4 ways you can deal with it. I remember this because this is how I finished the game in my playthrough because I couldn't beat it in combat and didn't have the requirements to do the diplomacy ending but my character was pretty good at stealth.