It is clear in Chapter Three, when Simon the Zealot is first introduced, that Simon and Rosh, although they may both oppose the same enemy in the form of the Romans, do so in very different ways. Rosh is of course a self-styled resistance fighter who is nothing more than a bandit who steals food from hardworking farmers around his lair. Simon continues his normal job and work, and refuses to join Rosh's group. Note how he explains his decision to not join Rosh and his men to Daniel:
When the one comes who will lead us, then we will all join together. In the meantime, as I said before, Rosh and I don't see eye to eye. For one thing, I prefer to earn my own bread and meat.
Simon, it is clear, sees through Rosh and recognises him for the petty bandit that he is. This is a realisation that only comes to Daniel later on in the novel. Both Simon and Rosh therefore are working to see their country free from the Romans and to get them out, but they work in very different ways.