All the people, even the tax collectors, when they heard Jesus’ words, acknowledged that God’s way was right, because they had been baptized by John. But the Pharisees and the experts in the law rejected God’s purpose for themselves, because they had not been baptized by John. Luke 7:29
This passage undermines Calvinism in a couple of ( interconnected) ways. It undermines the Doctrine of Double Predestination, Irresistible Grace and the way Calvinists normally conceive of Divine Sovereignty. The passage shows that God willed for people to be saved who would go on to reject him, which undermines Irresistible Grace. This also shows that God at some time willed for those who would become damned to be saved. In this passage, we are told that the Pharisees rejected God’s purpose for themselves, this purpose being recognized earlier in the verse as recognizing “God’s way was right” and being baptized by John for repentance and in anticipation of Jesus’s coming. So if the Pharisees rejected God’s purpose for them which included repentance and acknowledging God’s way was right, then God’s purpose for them was to turn from their sins and live. Yet they become condemned because they reject this purpose, and the passage explicitly identifies this as being against God’s will for them. According to Double Predestination, God determines who are damned and saved “unconditionally” apart from anything people do in this life and this will cannot be resisted. This verse shows that God’s will can be resisted and that those who become damned do not become so because God wills for them to be damned, but because they reject God’s purpose for them.
Secondly, this passage undermines the common Calvinist way of understanding Divine Sovereignty as being deterministic and as allowing little place for human freedom, especially with regard to spiritual matters. According to Calvinism, as far as saving faith is concerned, you only do what God wills for you to do. Your own will has no decisive impact on your salvation or lack thereof. However, this passage shows that people can decisively influence their own spiritual state and salvation by resisting God’s will for them to repent and acknowledge his ways as right.