The Bible story about doubt that most readily comes to my mind is that of the doubting Thomas in John, chapter 20. When his companion disciples told him that they had seen the risen Jesus, Thomas said, “unless I see the mark of the nails in his hands and put my finger in the mark of the nails and my hand in his side, I will not believe.” This is also the Gospel story for the Second Sunday of Easter every year, which, in turn, creates a tension between faith and doubt in the most important tenet of the Christian faith, the resurrection of Jesus. Another example of doubt is the story of Zechariah in Luke, chapter 1: When an angel appeared to him and told him that his aged wife, Elizabeth, would bear a son, Zechariah doubted God’s messenger, and was struck dumb until she did exactly that.

Doubt is an intellectual and emotional response to the uncertain and unknown in life. Although he would not take his companion disciples’ words as truth, Thomas was nonetheless curious: He yearned to see and touch for himself the nail marks on Jesus’ body, the marks of his crucifixion death. Deep down, he understood the mystery of resurrection: that there can be no resurrection without death, and that resurrection does not erase the wounds. His curiosity and desire led him not only to his life-changing encounter with the risen Jesus but also eventually to his own spiritual resurrection as an apostle. Zechariah, on the other hand, could not tolerate even for a moment the angel’s unexplainable and uncertain message. The paradox of Zechariah is that his preference for rational clarity stopped him from accepting the possibility of the impossible—the work of God’s grace. “How will I know that this is so?” he challenged the angel, and the work of God’s grace unfolded right before his eyes in silence. To his credit, he clearly changed in his heart and mind, as he followed the angel’s instructions in naming his new-born son John.

In his book, New Seeds of Contemplation, Thomas Merton wrote, “The function of faith is not to reduce mystery to rational clarity, but to integrate the unknown and the known together in a living whole, in which we are more and more able to transcend the limitations of our external self.” When it comes to faith in God, the doubt borne of the intolerance of uncertainty and driven by rational clarity can lead to a blindness to the mystery of God’s grace or even a denial of God, because God, by definition, is not fully knowable by human minds. God is an ever-unfolding mystery who desires a dwelling place in human hearts. This is why God’s grace is an intolerable uncertainty to those who seek only the rational certainty.

The doubt borne of curiosity, on the other hand, can inspire in us a courage of faith as we journey through life’s unknown and uncertain landscapes, learning to integrate the unknown and unexplainable mysteries of God into our daily living in a dynamic and concrete way. The unknown of life remains unknown. The uncertainness of God remains uncertain. We learn to integrate the unknown and the known, the uncertain and the certain, to live into the wholeness and the fullness of life. I believe it is impossible to live life solely based on rational certainty and clarity, intolerant of uncertainty. Doubt can arouse curiosity and courage in an amazing journey of grace and faith. In that sense, doubt is not the opposite of faith. Rather, doubt is an important part of our spirituality and faith.