Two Views of Regeneration
by John Hendryx

Monergism: In theol., The doctrine that the Holy Spirit is the only efficient agent in regeneration - that the human will possesses no inclination to holiness until regenerated, and therefore cannot cooperate in regeneration. The Holy Spirit, who joins us to Christ, quickens us through the outward call cast forth by the preaching of His Word, disarms our innate hostility, removes our blindness, illumines our mind, creates understanding, turns our heart of stone to a heart of flesh. Only then do we apprehend the beauty and excellency of Christ. This gracious Spirit wrought work in the heart gives rise to a delight in His Word -- all that we might, with our renewed affections, willingly & gladly embrace Christ. Monergism is when God conveys that power into the fallen soul whereby the person who is to be saved is enabled to receive the offer of redemption. It refers to the first step (regeneration) which has causal priority over, and gives rise to, the moral and spiritual desire/ability to comply with all the other aspects of the process of being united to Christ, (i.e., the ability to apprehend the Redeemer by a living faith, to repent of sin and to love God and the Mediator supremely) It does not refer to the whole process that it gives rise to (justification, sanctification), but only the granting of the spiritual capacity to comply with the terms of the covenant of grace. As Michael Haykin says, "The Reformation was not merely about justification through faith alone but, more importantly, it considered "...whether sinners are wholly helpless in their sin, and whether God is to be thought of as saving them by free, unconditional, invincible grace, not only justifying them for Christs' sake when they come to faith, but also raising them from the death of sin by His quickening Spirit in order to bring them to faith."

Synergism: "...the doctrine that there are two efficient agents in regeneration, namely the human will and the divine Spirit, which, in the strict sense of the term, cooperate. This theory accordingly holds that the soul has not lost in the fall all inclination toward holiness, nor all power to seek for it under the influence of ordinary motives." The synergistic doctrine of prevenient grace does not resolve this issue, but only pushes it back, for if all have grace and only some believe the gospel, then what makes them to differ? Jesus Christ or something else in them? According to the synergist, something other than grace makes men to differ. This unscriptural view is the greatest threat to a true understanding of salvation in the Church today.

The following chart highlights some of the major points of difference in these systems:

Synergism
Monergism
Cause of Regeneration
Regeneration is the work of Christ plus the good will of unspiritual man. What makes men to differ from one another is not the grace of Jesus alone, but Jesus plus the good will of unspiritual man. Regeneration is the work of the Holy Spirit alone applying the the effectual crosswork of Christ to the unspiritual man. What makes men to differ is Jesus Christ alone.
Faith is the cause that triggers regeneration Regeneration has causal priority to faith (Just as a person must have eyes before they see and ears prior to their ability to hear, so one must first have a new heart in order to understand spiritual truth)
Faith and affections for God are produced by the old nature. Faith is not produced by our unregenerated human nature. It is the immediate and inevitable product of the new nature. The new heart (by nature) loves Christ.
God and Man work together to produce the new birth. God's grace takes us part of the way to salvation, man's unregenerate will must determine the final outcome. In other words belief in Christ gives rise to the new birth. God, the Holy Spirit, alone produces regeneration with no contribution from the sinner (A work of God). The new birth is never spoke of in the imperative (not commanded), rather man must be born again by God.
God is eagerly awaiting the sinner's will. God effectually enables the sinner's will.
The persons of the Trinity have conflicting goals in accomplishing and applying salvation: The Father elects a particular people; The Son dies for a general people and the Holy Spirit applies the atonement conditionally on those who exercize their autonomous libertarian free will. The persons of the Trinity work in harmony - The Father elects a particular people (Eph 1:3-5), Christ dies for those the Father has given Him (John 17:9, 15; Rev 5:9) and the Holy Spirit likewise applies the benefits of the atonement to the same. (Regeneration is one of the redemptive benefits of Christ's work)
Restoration of spiritual faculties comes after the man without the Spirit exercizes faith with his natural (innate) capacities. Has the ability to see spiritual truth even before healed. (see 1 Cor 2:14). Has spiritual capacity/desire to receive the truth, prior God's granting any spiritual ability. "Light" itself is not enough for a blind man to see, his vision must first be restored. (John 3:3,6). Needs spiritual ability to receive truth prior to receiving it (1 Cor 2:12; John 6:63-65 & 37).
View of Humanity
The fallen sinner has the ability and potential inclination to believe even prior to the new birth The fallen sinner has no understanding, moral ability or inclination to believe prior to the new birth. (1 Cor 2:14).
There is enough good left in fallen man to turn his affections toward Christ. Fallen Man has a mind at enmity with God; loves darkness, hates the light and does not have the Holy Spirit. "There is no one who seeks God" (Rom 3:11); Sinner would never turn to God without divine enablement and new affections.
Sinner needs help, is spiritually handicapped. Spiritually dead sinner needs new nature (mind, heart, will), regeneration.
Natural man is sick and disabled like a drowning man so God would be uncaring if He didn't help by casting a rope. Natural man is spiritually impotent and morally culpable for sin. Our moral inability is not like a physical handicap or a drowning man for which we would not be culpable but, rather, it is like a man who cannot repay a squandered financial debt. Inability to repay, therefore, does not relieve us of the moral responsibility to do so. God, in His mercy, does not merely throw us a rope, He dives in to make certain we do not drown.
Needs salvation from the consequences of sin - unhappiness, hell, psychological pain. Needs salvation to remove the offense we've made against a holy God and from the power and bondage of sin.
The natural man is sovereign over his choice to accept or reject Christ - God conditionally responds to our decision. God's love for the sinner is, therefore, conditional. The natural man can contribute nothing towards his salvation. Faith is a response rendered certain following the efficacious work of the Holy Spirit. We respond to God's unconditional love. (Acts 13:48; John 6:37)
Those fallen men who are saved, either created a right thought, generated a right affection, or originated a right volition that led to their salvation while some others did not have the natural wherewithal to come up with the faith that God required of them to obtain salvation. Therefore salvation is dependent on some virtue or capacity God sees in certain men. Not Jesus alone, but Jesus PLUS... No Fallen man will create a right thought, generate a right affection, or originate a right volition that will lead to his salvation. We would never believe unless the Holy Spirit came in and disarmed our hostility to God. Therefore salvation is dependent on God's good pleasure alone (Eph 1:4, 5, 11), not some virtue or goodwill He sees in us.
Man's nature & affections do not determine or give rise to their choices. Even without the Holy Spirit working change in his heart, the sinner can still make a saving decision to believe the gospel. In this scheme God gives enough grace to place man in a neutral position which can swing either for or against Jesus. (An act of chance?) Man's nature determines his desires/affections and give rise to the choices he makes. Jesus bears witness to this: "No good tree bears bad fruit, nor does a bad tree bear good fruit." Luke 6:43 Only Christ can "make a tree good and its fruit will be good." (Also see John 8:34, 42-44; 2 Pet. 2:19).
View of the Gospel
The Gospel is an invitation The Gospel is not merely an invitation, but a command (1 John 3:23)
Christ died for all our sins except unbelief Christ died for all our sins including unbelief
Sinners have the key in their hands. Man's will determines whether or not Christ's death is efficacious. God has the key in his hand. God's eternal counsel determines to whom the benefits of the atonement apply.
It would be unjust of God to not give everyone an equal chance. If God exercized His justice then none of us would stand, since each of us is in active rebellion against an infinitely holy God. He owes us nothing and is under no obligation to save any person. Regeneration is, therefore, an act of pure, undeserved mercy because the justice we deserved, He poured out on His Son (thereby turning His wrath away from us).
After God makes one's heart of stone into a heart of flesh the Holy Spirit's call to salvation can still be resisted. After God makes one's heart of stone into a heart of flesh, no person wants to resist. By definition our desires, inclinations and affections have changed so we willingly and joyfully turn in faith toward Christ.
Salvation is given to fallen sinners (unregenerate) who choose and desire Christ of their free will. Apart from grace, there is no fallen sinner (unregenerate) who fits that description. A desire for God is not part of the old nature.
The grace of God is conferred as a result of human prayer It is grace itself which makes us pray to God (Rom 10:20; Isa. 65:1)
God has mercy upon us when we believe, will, desire, strive, labor, pray, watch, study, seek, ask, or knock, apart from his regenerative grace. To desire and seek God prior to the new birth is an impossible supposition. (Rom 3:11; 1 Cor 2:14) It is the infusion and quickening of the Holy Spirit within us that we even have the faith or the strength to will, desire, strive, labor, pray, watch, study, seek, ask, or knock and believe in the finished work of Christ.
Commands to repent and believe the gospel imply the ability of the sinner to do so. The Command toward sinners to repent and believe does not imply ability. Divine intent of the Law, according to Scripture, is to reveal our moral impotence apart from grace (Rom 3:20, 5:20, Gal 3:19,24). The Law was not designed to confer any power but to strip us of our own.
God helps those who help themselves. God only helps those who cannot help themselves. (John 9:41)
Unregenerate man contributes his little bit. Nothing in my hands I bring, simply to Thy Cross I cling.
Repentance is considered a work of man. Repentance is a gift of God. (2 Tim 2:25)
One of the greatest gifts God gives humans is to never interfere with their free will. The greatest judgment which God can inflict upon a man is to leave him in the hands of his own free-will. If salvation were left in the hands of the unregenerate sinners, we would indeed despair of all hope that anyone would be saved. It is an act of mercy, therefore, that God awakens the dead in sin to life since those without the Spirit cannot understand the things of God at all. (1 Cor 2:14)
With Man's will salvation is possible.

With man's will salvation (repentance and faith) is impossible, but with God all things are possible. (Matt 19:26; Rom 9:16; John 6:64,65) "Flesh gives birth to flesh, but the Spirit gives birth to spirit." John 3:6

Note: God acts unilaterally, taking the sole initiative in a free act of sovereign grace toward the sinnerógrace that is altogether prior to, and effectually produces, justifying faith. The response of faith from the sinner is penultimate as it stands next to the ultimate sovereign grace of God in monergism. As the first act of a newborn baby is to breathe, so the act of faith is the first act of the regenerated sinner, in his/her new birth in Christ.

For more on this topic
A Simple Explanation of Monergism by John Hendryx
The New Birth: Not the Consequence of Human Faith by John Hendryx (exegesis)
Ordo Salutis @monergism
What is Monergism? by John Hendryx
Monergism vs. Synergism
by John Hendryx
The Work of the Trinity in Monergism by John Hendryx
A Defense of Monergistic Regeneration by Gannon Murphy
The New Genesis by R.C. Sproul
A Short Response to the Arminian Doctrine of Prevenient Grace by John Hendryx

Multimedia
Monergistic Regeneration - Part I (MP3) Dr. Arturo Azurdia III
Monergistic Regeneration - Part II (MP3) Dr. Arturo Azurdia III