The thing that drives people to be converted to another lord are many things, the cause, the treatment, the fear one has of that being.
It depends on two things specifically, are the things the being is preaching clicking in your brain and does the person have the power to back up his claim.
It's about cause and a little showmanship. If I were to preach that justice is needed as a spice of life to the peasants that have been bullied by horrible barbarians, then by all means it is very possible they'll except my philosophy and join me to save the world.
But of evil barbarians whom desire to war upon people and believe the weak are worthless and the strong are master they might only be willing to accept a righteous task if that god shows them his power and why he deserves to be right.
This might be how it always happens but in rare cases it could go vice versa, the barbarians minds could be changed and the peasants might be too meek to desire to fight or defy anyone.
As a god (In this case and as, at certain times, convoluted as it seems) you must bring about a form of "Campaign" in order to exist. By whatever reason, desire, or purpose you have for your actions one thing remains true, you must convince the public you are worth their time.