Lets assume a ruling LG decides to end the world and take to heaven most souls. Forbidding suicide in his ethos he gave to his most faithful followers and paladins the order to kill all the population, especially the sinless ones.
1. How should paladins of that deity react?
2. Accepting the order, would paladins keep their status and alignment?
3. If some paladins refuse, can they still be paladin?
4. If paladins refusing loose their status, what should be their new alignment?
First off I have a problem with your assumption that a god would retain their LG status while doing so. I would honestly have every paladin that accepted that order fall, and the ones who disobeyed retain their powers, but if you control the morality system of your world.