Or despisest thou the riches of his goodness and forbearance and longsuffering; not knowing that the goodness of God leadeth thee to repentance?
Note 5 at Ro 2:4: This is a radical statement that the Jews of Paul's day and the religious legalists of our day reject. They refuse to accept that the goodness of God is sufficient motivation for people to turn from sin. They insist that fear of punishment is a superior motivator.
It is true that fear is a more familiar motivator to most people. Even a lost person or carnal Christian can identify with fear and respond to it. But as 1Jo 4:18 states, "Fear hath torment." Those who respond to God through fear will also be tormented with thoughts of doubt and condemnation as to whether they have done enough. Fear will move some toward God, but it is inferior to love. There is nothing that fear can do that love can't do better and without the side effect of torment.
Those motivated to seek God because of fear if they didn't will cease to be motivated when things are going well. They become the ones who only pray when they are in trouble. Those who come to God because of His goodness will see God as the source of their success and continue to serve God in the good and the bad times.
The world, and especially religion, has used negative reasons to motivate us. The Gospel uses the positive reason of God's great love to draw us unto God. We need to renew our minds to line up with God's thinking.