Every movement needs a slogan and the reformation produced many but perhaps the best known are the Five Solas.  They are: Sola ScripturaSolus ChristusSola GratiaSola Fide, and Soli Deo Gloria.  Sola means alone and an accident of Latin grammar changes sola's form to agree with the noun that follows.  The five solas are often stated in the single English sentence: Scripture alone, teach us that salvation is by Grace alone, through Faith alone, in Christ alone, to the glory of God alone.  As principals, they emerged from the protestant reformation as something of a central rallying cry.  They continue as such to this day with conservative protestants accusing the more liberal of not rallying around them at least as far as Sola Scriptura is concerned.  

Much of this page is based on The Cambridge Declaration of the Alliance of Confessing Evangelicals.  

 Sola Scriptura:  (Scripture alone)

Sola Scriptura is about the dichotomy of written versus oral tradition.  The reformation draws the skeptical line that we can be sure of what is written, and we can see that traditions have changed.  We therefore err on the side of caution and reject church tradition as a primary witness.  The point is that only the Bible is inspired and authoritative.  Further the Bible is accessible to all (that is, clear and self-interpreting). This doctrine is directly opposed to the teaching of the Catholic Church that Scripture can only be authentically interpreted through Holy Apostolic Tradition by the Magisterium (that is, the Pope and bishops at church councils). This doctrine is sometimes called the formal cause of the Reformation because it was the underlying cause of disagreement over Sola Fide.

It is perhaps ironic that while protestants will all agree on sola scriptura they will not all agree on the interpretation of scripture.  In my youth our church talked about "The Principal of Clarity," which we said allowed us not to have a formal doctrinal structure.  We said that a Christian fellowship could be organized around the essentials.  There in is the rub.  Defining the essentials.

SOLA SCRIPTURA

We reaffirm the inerrant Scripture to be the sole source of written divine revelation, which alone can bind the conscience. The Bible alone teaches all that is necessary for our salvation from sin and is the standard by which all Christian behavior must be measured.We deny that any creed, council or individual may bind a Christian's conscience, that the Holy Spirit speaks independently of or contrary to what is set forth in the Bible, or that personal spiritual experience can ever be a vehicle of revelation.(The Cambridge Declaration)

 

 Sola Gratia: ([teach us that salvation is by] Grace alone.)

The religions of man, even if they have started differently, have always collapsed into some sort of works-righteousness system or a system that is used to curry favor with God.  In reading scripture we find that the grace of God is found throughout.  God is faithful, it is mankind who is not.  There are religious things outlined in the Torah but they are intended to point us to God.  The sacrifices prescribed in the Torah are not sacrifices of placation, they are sacrifices of atonement and fellowship.  They are to bring the people into a right relationship with God.  In the stories of the wilderness wonderings it is the repentance the turns aside the wrath of God not the sacrifices, brazen serpents and such.  In the stories of the conquest of the land it is not the military might of Israel it is their reliance on God that produces the victory.  The land is not earned it is a gift, promised to Abraham and accepted by faith.

SOLA GRATIA

We reaffirm that in salvation we are rescued from God's wrath by his grace alone. It is the supernatural work of the Holy Spirit that brings us to Christ by releasing us from our bondage to sin and raising us from spiritual death to spiritual life.We deny that salvation is in any sense a human work. Human methods, techniques or strategies by themselves cannot accomplish this transformation. Faith is not produced by our unregenerated human nature. (The Cambridge Declaration)

 

 Sola Fide: ([through] Faith Alone)

The protestant notion of Justification (that is, becoming right before God) is that this becoming right comes through faith only, not good works, observing ceremonies or obeying laws.  It would not be true to say that faith is the end of Justification.  In fact in the classical protestant scheme, saving faith will always be accompanied by good works.  It may seem like splitting hairs but the Roman position was and to some extent is "Faith and good works yield justification."  This doctrine is sometimes called the material cause of the Reformation because it was the central doctrinal issue for Martin Luther. 

SOLA FIDE

We reaffirm that justification is by grace alone through faith alone because of Christ alone. In justification Christ's righteousness is imputed to us as the only possible satisfaction of God's perfect justice.We deny that justification rests on any merit to be found in us, or upon the grounds of an infusion of Christ's righteousness in us, or that an institution claiming to be a church that denies or condemns sola fide can be recognized as a legitimate church. (The Cambridge Declaration)

 

 Solus Christus: (in Christ alone)

Christ is the central person in the Christian faith.  This gets a bit difficult as Christians believe him to be God incarnate.   In Christ we see the very nature of a loving God.  The writer of the book of Hebrews compares Christ to angels, priest and sacrifice; in each case finding that Christ is superior.  So Christ provides us an example for right living, a substitutionary sacrifice for redemption and the mediation of a priest. 

SOLUS CHRISTUS

We reaffirm that our salvation is accomplished by the mediatorial work of the historical Christ alone. His sinless life and substitutionary atonement alone are sufficient for our justification and reconciliation to the Father.We deny that the gospel is preached if Christ's substitutionary work is not declared and faith in Christ and his work is not solicited. (The Cambridge Declaration)

 

 Soli Deo Gloria: (For God's Glory alone.)

We see from Scripture that the salvation of man is God's desired outcome.  It is not accomplished by the work or even the desire of man.  Man is constantly in a state of rebellion.  It is only God's grace that allows man to have fellowship with God.  Man finds his true freedom when he surrenders to the will of God and allows the Holy Spirit to live out a new life for him.  This is a paradox than most humans cannot accept.  It is, however, the nature of creation and the glory of God.

SOLI DEO GLORIA

We reaffirm that because salvation is of God and has been accomplished by God, it is for God's glory and that we must glorify him always. We must live our entire lives before the face of God, under the authority of God and for his glory alone.We deny that we can properly glorify God if our worship is confused with entertainment, if we neglect either Law or Gospel in our preaching, or if self-improvement, self-esteem or self-fulfillment are allowed to become alternatives to the gospel. (The Cambridge Declaration)