When my students write essays in which they take a side on an issue like this, I always suggest that they present the opposite point of view first (after the introduction, of course) so that their point of view can come last and therefore be more persuasive. Rhetorically, it is better to end with your point of view, not with that of the other side. So my organization for this would be to present the case that the Reformation was primarily economic and then to rebut that case and argue that the Reformation was largely a religious event.
I would talk about the idea that the people who participated in the Reformation were becoming more worldly as they became richer. These were people who had had the chance to travel and who were able to have access to printed materials. You might also talk about how the political leaders in parts of Germany were willing to embrace Protestantism in order to gain by being able to take property owned by the Catholic Church. Finally, you could mention that peasants felt oppressed by taxes imposed on them by landowners, including monasteries.
But I would then turn to the idea that the Reformation would never have spread if the religious ideas had not been compelling. I would argue that economics might have paved the way for the Reformation but that it was the ideas of the Reformation that gave it its appeal to the people. This is, ultimately, why the Reformation was successful.