By Chapter 17 of Exodus, we find Israel still complaining and God still faithful.  Instead of gratitude there was infighting.  In fact, they were ready to stone Moses for bringing them into the desert.  Once God gave them water to drink, then another problem occured, Amalek began attacking them and killing the weak straglers.  Israel was to deal with their own issues, then turn and deal with Amalek.  In the church today, we have the same issues.  church infighting leave us open to Amalek.