Monergism is the view within Christian theology which holds that God works through the Holy Spirit to bring about the salvation of an individual through spiritual regeneration, regardless of the individual's cooperation. It is most often associated with the Reformed tradition (such as Presbyterianism, low church Anglicanism and the Dutch Reformed Church) and its doctrine of irresistible grace, and particularly with historical doctrinal differences between Calvinism and Arminianism.
Most people naively imagine that there is something they can do to cause themselves to be born again. They hear a well-meaning person say, “Believe and be born again,” and suppose that they can. So they try to effect their own regeneration. But this they cannot do. In attempting it, they are like someone who imagines he caused himself to be born physically. Did he meet with his parents and ask to be born? Did he initiate his own birth? Of course not. The truth is, the initiative in birth lies outside of the one being born. He is merely part of a process that started long before he came into being. His parents acted, then God acted. And as a result, that individual was brought into the world. He did not cause his own birth to happen.
The same is true regarding spiritual birth. If you have experienced the new birth, it is not because you initiated it. Rather, it was an event that God brought about in you. More specifically, you were not born again because you exercised faith. In truth, the new birth preceded your faith and produced it. Saving faith is the fruit of regeneration, not the root of it. The biblically correct order of salvation—known in theological language as the ordo salutis—is not “Believe and be born again,” but the very opposite: “Be born again and believe.” The living God must act upon the spiritually dead soul and cause it to be born again. The new birth is by divine choice and sovereign initiative. God’s will affects the human will, not vice versa. Scripture intentionally uses the imagery of birth to underscore this essential truth of the sovereignty of God in regeneration.