Sola Scriptura, according to Scripture (the Word of God) Alone, is the affirmation that Scripture—the divinely inspired and infallible Word of God—is the ultimate rule and authority in matters of faith, worship, and morals. Specifically, what is necessary for salvation, righteous living, and the true worship of God must be proved from Scripture Alone. We affirm that Holy Scripture is Truth & Life, and contains all things necessary to salvation: so that whatsoever is not read therein, nor may be proved thereby, is not to be required of any man to be believed as an article of the Faith or necessary to salvation.

Sola Scripura DOES NOT mean that we are ruled by individual, arbitrary, ignorant, and subjective interpretations of Scripture divorced from the objective historic and doctrinal continuity of Christ's Church. Interpretation does not occur in a vacuum. We continue to consult tradition, history, reason, sound scholarship, theological consistency, and (chiefly) the Holy Ghost to guide us in the right interpretation of Scripture. However, it is ultimately Scripture that norms our Tradition, and not Tradition which norms the Scriptures.

...thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness: that the man of God may be perfect, throughly furnished unto all good works.
II Timothy 3:16-17

Therefore, brethren, stand fast, and hold the traditions which ye have been taught, whether by word, or our epistle.
II Thessalonians 2:15

...ye might learn in us not to think of men above that which is written, that no one of you be puffed up for one against another. For who maketh thee to differ from another? and what hast thou that thou didst not receive? now if thou didst receive it, why dost thou glory, as if thou hadst not received it?
I Corinthians 4:6-7

Sola Gratia, by Grace Alone, is the affirmation that Salvation is granted freely by the Grace of God Alone. It is not according to any merit, good works, or righteousness of our own but strictly according to God's good will. The Grace of God the Father is offered as a gift freely unto us, but at unfathomable cost to Himself (His Son upon the Cross). There is thus nothing we may do to earn God's gracious offer of salvation, nor anything we may do to void that gracious offer. God promises salvation to all those who turn unto Him, even those who once turned away.

But now the righteousness of God without the law is manifested, being witnessed by the law and the prophets; even the righteousness of God which is by faith of Jesus Christ unto all and upon all them that believe: for there is no difference: for all have sinned, and come short of the glory of God; being justified freely by his grace through the redemption that is in Christ Jesus: whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God; to declare, I say, at this time his righteousness: that he might be just, and the justifier of him which believeth in Jesus.
Romans 3:21-26

Sola Fide, through Faith Alone, is the affirmation that Salvation is received through faith alone—not by any works of Law OR some combination of faith and works. As St. Paul says in Romans:
For I am not ashamed of the gospel of Christ, for it is the power of God to salvation for everyone who believes, for the Jew first and also for the Greek. For in it the righteousness of God is revealed from faith to faith; as it is written, “The just shall live by faith.”
Romans 1:16-17

Faith is the human means whereby grace is redeemed for the believer. However, even this faith is a freely given supernatural gift of God, as St. Paul says in Ephesians:
For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: not of works, lest any man should boast.
Ephesians 2:8-9

Solus Christus, in Christ Alone, is the affirmation that there is no other name under heaven by which man may be saved, but that of Jesus Christ the Son of God. Scripture teaches us that we are incapable of perfectly following God's Law as His justice demands. Thus Jesus came to fulfill all righteousness on our behalf and become the atonement for our sins. Through faith in His incarnation, perfect life, death, resurrection, and ascension, we receive salvation by the means of His broken body and shed blood.

The word is nigh thee, even in thy mouth, and in thy heart: that is, the word of faith, which we preach; that if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved. For with the heart man believeth unto righteousness; and with the mouth confession is made unto salvation. For the scripture saith, Whosoever believeth on him shall not be ashamed.
Romans 10:8-11

Soli Deo Gloria, unto the Glory of God Alone, is the affirmation that the ultimate purpose of our salvation is to glorify God Almighty, and He alone receives all glory, laud, and honor for the work of salvation that He has accomplished for our supreme benefit. Salvation is not our work, but His alone—it is monergistic, "the work of one," God!

O the depth of the riches both of the wisdom and knowledge of God! how unsearchable are his judgments, and his ways past finding out! For who hath known the mind of the Lord? or who hath been his counsellor? Or who hath first given to him, and it shall be recompensed unto him again? For of him, and through him, and to him, are all things: to whom be glory for ever. Amen.
Romans 10:33-36