Has something happened, or not happened, in your life that has become a constant source of grumbling for you? Do you realize that grumbling (and, on the other side of the same coin, ingratitude) is offensive to God and damaging to your soul? This is the first in a new series on areas of “sin”—ways we fail to love God and love others—that are easy to overlook or justify. Rev. Duke Kwon Exodus 16:1–8; 17:1–7