A very, very dangerous thing to say, Jesus warned them.
"Therefore I say to you, every sin and blasphemy will be forgiven men, but the blasphemy against the Spirit will not be forgiven men. (Matthew 12:31) When Jesus healed the man with the withered hand in church, they attacked Him for doing it on the Sabbath.
And behold, there was a man who had a withered hand. And they asked Him, saying, "Is it lawful to heal on the Sabbath?" that they might accuse Him. (Matthew 12:10)They were so doctrinally aggressive that church members and even the leaders were frightened of disagreeing with them.
The parents of the blind man who was healed were frightened to say that it was Jesus who had healed their son for fear of the Pharisees driving them out of the church.
His parents said these things because they feared the Jews, for the Jews had agreed already that if anyone confessed that He was Christ, he would be put out of the synagogue. (John 9:22)Even the Jewish leaders were intimidated by them and would not disagree with them lest they should be put out of the church;
Nevertheless even among the rulers many believed in Him, but because of the Pharisees they did not confess Him, lest they should be put out of the synagogue; (John 12:42)In this case because they wanted man’s favour more than God’s
for they loved the praise of men more than the praise of God. (John 12:43)Their opposition to God’s Spirit at work divided the church.
“This fellow isn’t from God because He’s working on the Sabbath” Others said, “But how could an ordinary sinner do such miracles” And so there was deep division among them. (John 9:12) They could pull down but could never build up. Their spirit ran contrary to God's Spirit who says
Brethren, if a man is overtaken in any trespass, you who are spiritual restore such a one in a spirit of gentleness, considering yourself lest you also be tempted. (Galatians 6:1)We read in the Bible where they derided,
Now the Pharisees, who were lovers of money, also heard all these things, and they derided Him. (Luke 16:14)Where they reviled,
Then they reviled him and said, "You are His disciple, but we are Moses' disciples. (John 9:28)Where they complained,
And the Pharisees and scribes complained, saying, "This Man receives sinners and eats with them." (Luke 15:2)Where they plotted against
Then the Pharisees went out and plotted against Him, how they might destroy Him. (Matthew 12:14)Where they assailed vehemently, where they cross examined,
And as He said these things to them, the scribes and the Pharisees began to assail Him vehemently, and to cross-examine Him about many things, (Luke 11:53)Where they disputed and tested,
Then the Pharisees came out and began to dispute with Him, seeking from Him a sign from heaven, testing Him. (Mark 8:11) Jesus was the Word become flesh and yet they were stricter than Jesus.
"For they bind heavy burdens, hard to bear, and lay them on men's shoulders; but they themselves will not move them with one of their fingers. (Matthew 23:4)They confronted Him, and His disciples, about not keeping the Sabbath holy.
And when the Pharisees saw it, they said to Him, "Look, Your disciples are doing what is not lawful to do on the Sabbath!" (Matthew 12:2)They questioned Jesus on issues such as adultery, and divorce. But they questioned Him, in their spiritual arrogance, not to learn from Him, but to 'test' Him and try to theologically catch Him out in His teaching.
Mt 19:3 The Pharisees also came to Him, testing Him, and saying to Him, "Is it lawful for a man to divorce his wife for just any reason?" (Matthew 19:3)They tried to trap Him on the question of allegiance to the governing authorities.
Then they sent to Him some of the Pharisees and the Herodians, to catch Him in His words. (Mark 12:13)
"Tell us, therefore, what do You think? Is it lawful to pay taxes to Caesar, or not?" (Matthew 22:17) They were so sure, so absolutely certain, that their zeal for 'truth' was godly and that God would be well pleased with their 'ministry'
However Jesus came with grace and truth
And the Word became flesh and dwelt among us, and we beheld His glory, the glory as of the only begotten of the Father, full of grace and truth John bore witness of Him and cried out, saying, "This was He of whom I said, 'He who comes after me is preferred before me, for He was before me.'" And of His fullness we have all received, and grace for grace. For the law was given through Moses, but grace and truth came through Jesus Christ. (John 1:14-17)