Irresistible Grace? Not in the Bible!
The "I" in TULIP stands for Irresistible Grace, and like the rest of that Calvinist acronym, it has no basis in Scripture. Check out the convoluted definition of this term provided by the Calvinist website, CARM, and the direct contradiction between the first two sentences and the last sentence:
"The term, unfortunately, suggests a mechanical and coercive force upon an unwilling subject. This is not the case. Instead, it is the act of God making the person willing to receive him. It does not mean that a person cannot resist God’s will. It means that when God moves to save/regenerate a person, the sinner cannot thwart God’s movement and he will be regenerated."
So it's not a mechanical coercive force, buuut the person to whom this force is applied can't do anything about it and has no choice in the matter. What?! Actually, this kind of double-speak and word gymnastics are pretty standard in Calvinist explanations of things that are entirely unbiblical.
In plain language, Irresistible Grace means that God forces people to believe on Him. They believe (though they won't phrase it this way) that God forces certain people to be saved and forces everyone else to go to Hell. So much for God being the embodiment of love (1 John 4:8), eh?
Dave Hunt succinctly refuted this idea when he said, "Surely the continual disobedience both of unbelievers and believers proves that God’s grace is not ‘irresistible.’ Nor does man’s disobedience diminish God’s sovereignty in the least. Obviously, freedom of choice itself is part of God’s plan!"
Romans 1 makes it clear that nobody will have an excuse when they stand before God. God has made Himself known to the world through creation, having written His law on our hearts, and has manifested Himself to all! Since God has reached out, it is on us to respond to His calling.
If we didn't have a choice in the matter, it would nullify the entire Bible where from cover to cover God pleads with people to turn to Him. Only a cruel and manipulative God would implore mankind to put their faith in Him, and then not allow them to do so.
1 Timothy 2:4 says that God desires "all men to be saved, and to come unto the knowledge of the truth." This message is consistent with the whole Bible.
Irresistible Grace is an absolutely nonsensical doctrine.