The foundational doctrine of Calvinist theology is Total Depravity. It is the "T" in TULIP
(TULIP is an acrostic used to spell out the five points of Calvinism). The remaining four points of Calvinism (Unconditional Election, Limited Atonement, Irresistible Grace and Perseverance of the Saints) are built upon the foundation of Total Depravity.
John Piper, one of the leading teachers of Calvinism today, defines four senses in which mankind is totally depraved:
(1) Our rebellion against God is total. Apart from the grace of God there is no delight in the holiness of God, and there is no glad submission to the sovereign authority of God.
(2) In his total rebellion everything man does is sin.
(3) Man's inability to submit to God and do good is total.
(4) Our rebellion is totally deserving of eternal punishment.
The upshot of Total Depravity is that it is impossible for any person to come to God of their own volition. Therefore, the only way a person can come to God is if God predestined them and enables them to come. Only those who have been thusly "elected" by God can become true followers of Jesus. The rest of mankind--those who were not predestined for salvation--are, ipso facto, predestined for eternity in Hell. Another ramification is that if one is among the predestined elect, it is regardless of whether or not one lives a life of holiness.
Presbyterian churches are Calvinist, as are most churches that use the word "Reformed" in their name. Seattle's mega Mars Hill Church is Calvinist.
Many Christians who do not attend Calvinist churches or even know what Calvinism is have imbibed elements of Calvinist theology. In particular, the doctrine of Total Depravity is widely accepted among Christians who otherwise would not self-identify as Calvinist. This tends to lead to a defeatist attitude towards avoiding sin on a day-to-day basis. "There but by the grace of God go I", as the saying goes. The typical Evangelical Christian struggles with the notion, which they have been told is Biblical, that there is nothing good in them. They have to try to overcome sin in their life, but it is a foregone conclusion that they will always ultimately fail due to their Total Depravity.
Quakerism arose in the 17th century, in part, as a reaction against Calvinist theology. Probably the most controversial doctrine of Quakerism is the doctrine of Perfectionism. It is also probably the most misunderstood doctrine of Quakerism. Perhaps it would have been better to call it "Maturism" or "Obediencism".
At the core of Quakerism is the belief that God can be experienced here and now. George Fox's seminal revelation was that "Christ has come to teach His people Himself." This means that one can walk continuously in the "Inner Light" of Christ's presence, receiving wisdom, direction, encouragement, instruction and the ability to overcome temptation.
Thus, to the Quaker, it is possible to walk in obedience to God, and to not sin.
Here's another way to think of it: Can you go for one minute without sinning? Total Depravity would say "No, even if you are not actively sinning, you are still filled with sin." Perfectionism would say, "Yes, since to sin is to walk outside of God's will, if one stays within God's will for one minute, one has not sinned for that minute." If one minute, how about two? If two, how about five? If five, how about fifteen? If fifteen, how about an hour? If an hour, how about a day?
The upshot of Perfectionism is that it is remarkably optimistic. Since sin is something which enslaves and degrades us, Perfectionism says that we have the potential, by walking closely with God, to live in freedom and dignity. It should be stressed that Perfectionism isn't about earning God's approval. God's love, as demonstrated through Christ, is a pre-existing condition. Therefore, if we stumble and sin, we have not lost God's love and acceptance. As Philip Yancey once wrote, "There is nothing you can do to make God love you more than He already does. There is nothing you can do to make God love you less than he already does." This is because God's love is perfect and it is all about Him, not us.
However, the joy of the Christian life (what Quaker Hannah Whitall Smith called "The Christian's Secret of a Happy Life") is going through our days in a living, interactive, dialogical relationship with God, fully aware of His passionate and unchanging love for us. As we do so, we naturally and progressively live more and more within God's will. We grow into Him. We also begin to reflect Him to the world in which we live. This is why Quakers have so often been at the forefront of human rights and social justice movements.
When I read in Matthew 3 about John the Baptist and his call to the ancient Jews to "Prepare the way for the Lord, make straight paths for Him." by repenting from sin (and being baptized as a way of publically signifying that repentance), I see the same principle of what came to be called Perfectionism. The Greek word translated as "repent" is 'metanoia', which literally means to have a change of mind; a reorientation; a fundamental transformation of outlook; a whole new way of thinking. John Newton wrote "I once was lost, but now am found, T'was blind but now I see." He experienced metanoia. When Jesus told Nicodemus to be "born again" He was telling him to start all over again with an entirely new way of thinking. Metanoia.
The Biblical Book of James is all about choosing to walk in obedience with God. James tells us that "...the testing of your faith develops perseverance. Perseverance must finish its work so that you may be mature and complete, not lacking anything." James then cajoles us to "...get rid of all moral filth and the evil that is so prevalent and humbly accept the word planted in you, which can save you." (1:21 -- It should be mentioned that, Biblically speaking, the "Word" is Jesus; what Quakers would also call "the Light"). James goes on to tell us that "...faith by itself, if it is not accompanied by action, is dead [literally, "is a corpse"] ... Show me your faith without deeds, and I will show you my faith by what I do." (2:17,18) Later he instructs us, "Submit yourselves, then, to God. Resist the devil, and he will flee from you. Come near to God and He will come near to you. Wash your hands, you sinners, and purify your hearts, you double-minded. Grieve, mourn and wail. Change your laughter to mourning and your joy to gloom. Humble yourselves before the Lord, and He will lift you up." (4:7-10) This is repentance. This is metanoia. Quakers call it "Convincement." James may make it sound like a downer, but it is the gateway to walking closely and joyfully with God, in victory over sin. This is what the doctrine of Perfectionism is all about.
If you read the first three chapters of the Book of Revelation, you will see a phrase repeated over and over: "To him who overcomes." What follows each instance are promises to the one who overcomes. In fact, the entire Book of Revelation, rather than being a freaky prediction of end-times events, is a document written to encourage Christians to walk closely with God during tough times and to "overcome" rather than be overwhelmed.
When Moses gave his farewell address to the ancient Hebrews (as recorded in Deuteronomy 30:11-14) he offered them this challenge: "Now what I am commanding you today is not too difficult for you or beyond your reach. It is not up in heaven, so that you have to ask, 'Who will ascend into heaven to get it and proclaim it to us so we may obey it?' Nor is it beyond the sea, so that you have to ask, 'Who will cross the sea to get it and proclaim it to us so we may obey it?' No, the word is very near you; it is in your mouth and in your heart so you may obey it."
One thousand years later, God gave the prophet Jeremiah a similar message: "I will put my law in their minds and write it on their hearts. I will be their God, and they will be my people. No longer will a man teach his neighbor, or a man his brother, saying, 'Know the Lord,' because they will all know me, from the least of them to the greatest. ... For I will forgive their wickedness and will remember their sins no more." (Jeremiah 31:33-34)
These messages, and many more like them, form a thread which runs all through the Bible. It is an invitation to live moment-by-moment, day-by-day, in the tangible presence of God and, as a result, to be radically changed from the inside-out to one who is not totally depraved, but is mature, obedient and filled with light, life and love.