Pelagianism is a system of theology named after it's chief proponent, Pelagius. Pelagius was a British monk who opposed Augustine's doctrines of God sovereignty over men. In Augustine's Confessions he wrote a prayer that said essentially "God, command what thou will; and will what thou commandest." Put into modern language Augustine says "God command what you want and give us the power to obey your commands." Augustine knew that depraved sinners were totally reliant on God to enable them to do anything spiritual. We cannot do a godly thing unless God empowers us to do it.
Pelagius saw this prayer and rebelled at the theology it was based on. Pelagius believed that men have the natural capacity to do what God commands. He believed God would not command men to do anything they were not capable of doing. Pelagius built a system of theology around this idea of man's natural ability to obey.
So what does Pelagianism teach? Pelagius denied that the sin of Adam is passed onto men and that men are born with a sin nature. Instead, he believed humans were born morally neutral. They were neither saint nor sinner. He taught they were tabula rasa, a blank slate. Men (and I use this term generically in this article), learned to be sinners by copying the examples of the people around them. If we are raised by sinners then we will be nurtured to be sinners. But our wills are free and can choose to follow better people. Pelagius taught that Jesus came to the earth to give men a better example to follow. By rejecting the sinfulness we had been taught and choosing to obey the example set by Jesus, men could learn to become holy and thereby, save themselves. Pelagius taught that Jesus' death on the cross was an example of a person's supreme sacrifice in service to humanity. He taught that Christians were people who followed Jesus' way of life and his teachings. He believed that following Jesus would lead to a life of service to humankind and ultimately to a righteousness that was worthy of salvation. The bottom line in all this was that it was by men's free choices to be obedient to the commands of God as given through the life of Jesus that brought men to salvation. In short, it was a salvation earned completely by men. Man saved himself.
The universal Church at the time gathered together at the Council of Orange and considered the controversy between Pelagius and Augustine. In the end, they declared Augustine to be the defender of the biblical viewpoint and they called Pelagianism a heresy.
You may be asking what difference all this makes. I will answer with this ... every ancient heresy of the Church is being taught somewhere today. You may say to yourself that "No one believes they save themselves." But I will tell you honestly that Pelagianism is being taught today in many places. Not just in cults and off the wall churches, but you can find Pelagius' teachings in some pretty well known and even well respected ministries.
The heart of Pelagianism is man contributing to his own salvation. That is an idea that sets well with a lot of people today. It is popular for men to want to be the captains of their own souls. The idea that God rules over men's souls is not well received in many places today. Biblically, God always brings men to the point of helplessness before he steps in. In Exodus, we see God leading the Hebrews to the shores of the Red Sea, giving them nowhere to run when Pharaoh's chariots came to attack them. The Hebrews were defenseless, helpless, and out of options. One could say that there was no way they could have saved themselves. But Moses commands them to "Stand still and see the salvation of the Lord." At that time, God saved the Hebrews. God opened the sea. God blocked the Egyptians with fire. God lead the people through the waters. God closed the sea on the Egyptian army. Salvation was all of the Lord.
Friend, God is the same, yesterday, today and forever. Salvation is still all of God. Beware Pelagius' heresy. Reject every teaching that says that you help God with your salvation. Any concept that God does his part and you do yours ought to be shunned like the plague. We are not co redeemers with God. We are slaves of sin and helpless beggars, pleading with God for mercy. We offer him nothing and He owes us nothing. But we have his promise that everyone who comes to Christ for salvation will find it and be saved. Beloved, plead with God for that salvation that He purchased with the blood of the God-man Jesus Christ. Plead until God assures you that the promise is yours and that you are Christ's. And when that day comes and you know that you know that Christ died for YOUR sins personally then, praise God that even though you were a sinner ... that He SAVED YOU anyway.
As the Reformers taught ... Soli Deo Gloria .. to God alone be the glory! That is the way it always should be. Amen.