Certainty is the enemy of faith.
In John 5, Jesus is accosted by Jewish leaders for breaking the Sabbath. After some back and forth, Jesus says that the Father will show even greater works than this, "so that you will be astonished" (Jn 5:20 RSV).
Don't bet on it. The Pharisees of Jesus' day are often portrayed as meticulous rule-keepers, legalists intent on following every letter of every law. There is certainly some truth to this portrayal, but it may miss a deeper truth. As Genevieve Glen writes, "No matter how carefully and thoroughly we think we have defined God, ... God escapes and becomes once again the uncontrollable 'more.'"*
The Pharisees suffered from a failure of imagination. They were certain, dead certain, that they had God all figured out, not realizing that the living God was always beyond their grasp. Even when Jesus worked miracles right before their eyes, they failed to be astonished.
For some of us, Lent is a time of meticulous rule-keeping, avoiding sweets, doing this or not doing that. These ascetic disciplines have their value, just as the Pharisees' observance of the commandments also had value. But the heart of faith is not obedience. The heart of faith is wonder, astonishment, gratitude, and awe.
May this Lent be a time to stretch our imaginations, to loosen our grip on some of our certainties. May this Lent be a time to open ourselves to wonder and astonishment.