The Claims of Jesus
From the Catechism of the Catholic Church, Simplified
The Real Stumbling Block - Forgiving Sins (587-589)
The real stumbling block for Israel's religious authorities was Jesus' role in the redemption of sins.
Jesus scandalized the Pharisees by eating with sinners (Lk 5:30), he had not come "to call the righteous, but sinners to repentance" (Lk 5:37). He said that sin is universal and that anyone is blind who claims not to need forgiveness (Jn 8:33-36).
Jesus gave scandal by saying that God the Father was also merciful (Mt 9:13) and by hinting that he (Jesus) could admit sinners to the messianic banquet (Lk 15:1-2). However, the great dilemma was caused by Jesus' forgiving of the sins of the paralytic. The authorities correctly asked "Who can forgive sins but God alone?" (Mk 2:7). By forgiving sins Jesus was either blaspheming (making himself equal to God) or he was speaking the truth.
Believing His Claims (590-591)
Jesus said that a person "greater than Jonah, greater than Solomon, greater than the temple is present" (Mt 12:41-42). These words are justified only if Jesus is God. This is true also of Jesus' other claims: "Before Abraham was, I am" (Jn 8:58) and "I and the Father are one" (Jn 10:30).
Jesus asked the authorities to believe because he did the works of God (Jn 10:38). Such a demand for belief throws light upon the Sanhedrin's misunderstanding of Jesus. They condemned him as a "blasphemer" (Mt 26:64-66) due to ignorance and "hardness of unbelief" (Lk 23:34).