The response of the Synod of Dort to the doctrine presented by the 'Arminians' that man could resist the grace of the call to salvation by the Holy Spirit was a reiteration of the biblical truth that God calls those whom He has chosen. (Romans 8:30) In other words, the elect cannot resist the call to salvation by the Spirit. In view were two separate but similar doctrines of the Gospel call.
The first doctrine both 'Calvinists' and 'Arminians' hold strongly. The Gospel message is to be preached to every person and every person has a responsiblity to respond to the Gospel message. In fact, everyone who hears does respond to the Gospel. They either accept it, or they reject it. 'Calvinists' affirm this wholeheartedly. It is affirmed in scripture first, that the Gospel is to be preached to every creature (Matthew 28:18-20, Acts 1:4-8), and second, that not everyone who hears the Gospel become Christians. (The Book of Acts) Although hyper-calvinism disagrees with the rest of Christianity that the Gospel is to be freely preached, 'Calvinism' as a whole affirms (and practices?) the freeness of the Gospel message.
The second doctrine was the sticking point. 'Calvinists' believe that when the Gospel call is accompanied by a gracious, inward call by the Holy Spirit, that this grace is 'irresistible', while the 'Arminians' believe that the call by the Holy Spirit can be resisted. Let's explore this further. 'Calvinists' and 'Arminians' both believe in two calls, one in the proclamation of the Gospel by man, and another by the Holy Spirit. However, 'Calvinism' affirms that while the outward call by the preacher can be resisted (and often is), that the inward call by the Holy Spirit cannot be resisted.
The real issue in view goes back to 'Total Depravity'. Just how much of man was affected by the fall of Adam? (Genesis 3) Or, more to the point, was the will affected in such a way that man loses the ability to respond positively to God? If you recall, we found that sin permeates all of man's being, and specifically that sin affects the will negatively. (Romans 3:11-12) This is an important point because if man can choose God without having his will renewed by the Holy Spirit, then conversely, he should not be able to not choose God when the Holy Spirit is calling him. Or is the Holy Spirit in view at all in the 'Arminian' statement? Many 'Arminians' believe that no work of the Holy Spirit is necessary until after a choice has been made for Christ. Then the Holy Spirit begins His work. 'Calvinists' affirm consistently with the writers of Scripture that, in order for man to be saved, the Holy Spirit must make him willing because apart from that work of the Spirit, man will never choose Christ. (John 3:5-8)
Two widely believed misconceptions about this doctrine is that 'Calvinists' believe that everyone that God has chosen will come to faith regardless of (1) whether or not they want to, and (2) regardless of the preaching of the Gospel. These are simply not true. (1) 'Calvinists' believe that no one is willing to believe (Romans 3:10-18) until this special work of the Holy Spirit is performed in them at which point they become willing. (2) 'Calvinists' believe that the preaching of the Gospel is God's appointed means of working by His Holy Spirit and that when the Gospel is preached the Spirit works in some of those who hear and they, as a result of the outward call of the preacher and the inward call of the Holy Spirit, come to faith in Chirst. (I Corinthians 1:18-2:5)
No one seeks after God. We are the enemies of God. We are dead in our sins. The gracious inward work of the Holy Spirit gives us life in order that we may seek peace with God through faith in Christ. (Ephesians 2:1-10) Our confidence in preaching is in the Holy Spirit's work of regeneration and not in our own abilities. Those He has chosen, and redeemed by His own blood, He also calls.