As I have said several times, the term "irresistible grace" is a confusion begging choice of words. It was probably chosen to provide an "I" in "TULIP."
The better choice, in my opinion, would be "Efficacious Grace" but "TULEP" doesn't spell anything!
God's redeeming Grace is efficacious. That simply means that it accomplishes exactly what God intended it to accomplish. God's efficacious Grace never fails.
When I am forced to defend the term "irresistible" I do so in this way. Irresistible Grace is like that last piece of Pecan Pie in the refrigerator. I was looking for a late-night snack and just couldn't resist that last piece of pie. It looked so delicious. Smelled so delicious. Not only didn't I resist, I didn't want to resist!
God, through His Efficacious Grace, makes Christ so magnificent, so compelling, so desirable, that we not only don't resist, we no longer want to resist.
Remember the Hornet Song?
When the Canaanites hardened their hearts against God
And grieved Him because of their sin,
God sent along hornets to bring them to time,
And help His own people to win.
The hornets persuaded them that it was best,
To go quickly, and not to go slow;
God did not compel them to go 'gainst their will,
But He just made them willing to go.
Chorus
He does not compel us to go, No! No!
He does not compel us to go.
He does not compel us to go 'gainst our will
But He just makes us willing to go.
And that is what Efficacious Grace is.