Doubt In The Face Of Suffering

To doubt is to be uncertain about God and to feel isolated from him; to suffer is to experience pain and to feel isolated from others. Giant Despair thus appears and imprisons us in what Bunyan aptly called “Doubting Castle.” There, alone in the darkness, we begin to hear and believe the voices that say “there is no help for him in God” (Ps. 3:2 kjv).
But it is not true that there is no help for us in God! Hear the testimony of others: “Because the Sovereign Lord helps me, I will not be disgraced” (Isa. 50:7); “God is our refuge and strength, an ever-present help in trouble.… God will help … at break of day” (Ps. 46:1, 5).
The problem for the doubting sufferer, however, is that “break of day” has not yet come. It is still dark. When doubt is at its height and attacks most fiercely we ask, “Is there no light to help me through the night?”
Indeed there is; but the prescribed antidote tends to work slowly. It is important for us, therefore, to complete the course.
Scripture’s account of genuine spiritual experience speaks to your situation. It describes your symptoms and illustrates the way of recovery. You are not unique. There is no test of faith that seizes us “except what is common to man. And God is faithful; he will not let you be tempted beyond what you can bear” (1 Cor. 10:13). Great saints of God have been where you are now.

Source - Sinclair Ferguson quoted in Sproul, R. C. (2000, c1993). "Doubt & Assurance" Grand Rapids: Baker Book House.