Look at the focus of trust for each religion. Christians come to God, not by their effort to get over the wall, but by trusting Christ and passing, in His way, through the wall. Christians depend, not on their own work, but on God’s great work on their behalf. In other words, they place their trust for salvation in Jesus the Messiah (the Christ).
Followers of Judaism, as yet, claim no universal Messiah, so their trust must be placed elsewhere. Inevitably, their trust comes to rest in themselves. They think that God accepts them when they measure up to all the laws and traditions of their forefathers. But how does one measure up? By working very hard! They come to depend on their own hard work, their own morality, their own achievement of piety. This amounts to trusting in oneself. Paul calls it “confidence in the flesh,” that is, reliance on human efforts and qualities (Philippians 3:4). Luke 18:9 says they “trusted in themselves that they were righteous.” As the Pharisee’s prayer goes on to show (Luke 18:10-14), this religion honors the creature more than the Creator. It relies on a kind of human perfection and fails to rely on the One who is perfect, the God who alone is powerful to save. What a perversion of the truth about God and man!