There could be potential frustration for a pastor to tell of God's glory and grace, only to have souls nod their head in an intellectual agreement which is tottering on boredom for "old news"; yet we preach by faith (not frustration), knowing God will bring the truth deeper than the mind all the way to the heart. Because this is the work of God, we are free to rest in His power, and so we proclaim His goodness with freedom and joy.