I am a defender of sola scriptura (along with the other 4 solas of Protestantism) at least according to the following understanding: The Bible is the only authority put into human hands for the contents and teachings of Christianity. In particular God has not given over such authority to sinful human beings. God only gives authority to the written word, for much the same reasons that we have learned to keep the law of the land in written form.
Jesus gives authority to scripture but never explains what texts exactly scripture consists of. It is a situation which is very uncomfortable for the scribes and lawyers (legalists) among us. The presumption seems to be that consensus is enough to identify what should be called scripture and thus it is natural to rely on the earliest ecumenical decision on this. Along with the creed of Nicea this canon simply defines the Christian religion and that is all.
"Sola gratia", grace alone: Salvation is by the grace of God alone – 100% a work of God. But salvation is not a ticket to heaven but a transformation of self into goodness - a realization of our true potential and so salvation is not independent of works and thoughts and beliefs. We are not saved by works but we are saved to works. And no there is no condition on this that God only works for your salvation if you are a Christian or if you believe in Him.
In Matthew 19:16, a man came to Jesus asking what he must do to have eternal life. Ultimately Jesus answer is given in verse 26, “with men this is impossible, but with God all things are possible.” This is not something we can do, ever. Asking what is enough and we already going in the wrong direction.
"Sola Fide", faith alone: Faith alone is what God asks of us for salvation. This is not a contradiction because this is not about what accomplishes our salvation, but about the process by which God accomplishes it. But no, faith is not some sort of magical power or belief that God bestows upon us so that by this power or belief we can save ourselves! First and foremost this salvation through faith stuff means that God is not operating on an inanimate object, but with those who have will and choice that cannot be left out of it. So part of the process of salvation is that however much God may have to work to liberate our free will so that we can do so, God requires us to make a choice. Either we can go the way of our own desire or understanding that God’s desire for us is so much better, to choose that instead. This is NOT a surrender of our free will but an exercise our free will to choose the direction which God would lead, and the fact of the matter is that the direction that God would lead us is to the increase of our free will. Life does not suddenly become simpler for the person that follows God’s lead, because it is not about God telling him what to do all the time. It becomes more complicated because God makes him aware of choices he would never have imagined otherwise.
But there is a second part to the salvation through faith business. And that is in answer to the question, how do we know? The answer is through faith. We make a choice and we put our trust in God and that really is all there is to it. So do I know that I know that I am saved? Give me a break! You can keep such invitations to self brainwashing. How can it be salvation through faith to buy into this promise that I never need have faith again because “I know”. Just like love, this is well within the realm where belief creates reality. If we don’t believe in it then it cannot be, but there comes a point where you have to understand that life is not just about objective observation but also about subjective participation.
Romans 10:5 Moses writes that the man who practices the righteousness which is based on the law shall live by it. 6 But the righteousness based on faith says, Do not say in your heart, “Who will ascend into heaven?” (that is, to bring Christ down) 7 or “Who will descend into the abyss?” (that is, to bring Christ up from the dead). This is the difference between faith and legalism, thinking you have some way to determine who is saved and who is not.
"Sola scriptura", scripture alone: The Bible is the only authority given into the hands of men. God does not give authority to men themselves because God does not do things that are not in our best interest, and the flaws of human beings are such that power corrupt them. So God does not give His word to men directly so that they have authority to speak for Him. God only gives authority to the written word, for much the same reasons that we have learned to keep the law of the land in written form.
Jesus invested authority in the scriptures, because as the consumate example for how we should live our lives, Jesus contantly turned to the scriptures Himself as the source for what God says to human beings. This tells us that the Scriptures are a product of the work of God, and thus He is the author using the events of history and human writers as His intruments. This means the scriptures say exactly what God intends and does not require correction by the work of an interpreter. This does not mean that the Bible is self-interpreting, or that people cannot twist the words to mean things contrary to God’s intent. But it does mean that for a person who sincerely seeks God, the Bible is where He should look to see what God would say to Him.
But we must also understand that the purpose of the Bible is not to teach us the truth about all things (it will not tell you how to fix your computer). It is not your savior and you will not find eternal life by studying them, for Jesus tells us its purpose in John 5:39-40, which is to bear witness to Him, so that we may come to Him. He is the savior and it is only in a relationship with Him that we will find eternal life.
"Solo Christo", Christ alone: There is only one mediator between man and God and that is the Christ. All over the world there are religions that promise salvation if you will believe what they say and do what they tell you to do. All over the world you will find gurus and priests who will offer to mediate between you and God, telling you what God has to say to you, accepting your confessions on God’s behalf, and hearing what you would ask of God. But the gospel is telling you that all of these promises and offers will mislead you even if it is not an intentional deception, for God desires to have a personal relationship with you in the person of Jesus, who is God Himself. God does not require a human being in order to speak to you, hear your confession or answer your prayers. So do not believe it when they tell you what you have to do or to believe in order to be acceptable to God. If religion has been made into a means by which people manipulate you then you have been deceived.
Ephesians 5:23 Christ is the head, leader, organizer and authority over His own church, with a personal relationship with every member of that church and so no matter what services may be offered and accepted between two members of that church, no authority is given in such relationships to any person by God, but only by the members themselves according to mutual agreement.
"Soli Deo gloria", glory to god alone: In Matthew 23:8-11, Jesus said to call no human being teacher, for we are all bretheren, and to call no human being father because we have one Father in heaven, and to call no human being master, because Jesus is our only Lord. If we would acheive greatness – if we would seek to be like our God, then we should humble ourselves to serve one another just as God has humbled Himself to serve us by becoming a human infant and dying on the cross.
Jesus said in 18:19, “Why do you call me good? No one is good but God alone.” This tells us three things. First is if Jesus points to God as the only example of what is good then certainly we should only point to God in the same way. He is showing us that no matter how righteous in thought and action we may be, it is not good for us to allow ourselves to be the example which people hold up to follow. Second, He is showing us that part of being good is about seeing the goodness of God and the goodness in others rather than in yourself. It is to love others and live for the sake of others. Thirdly it is telling us about the character of God (For I ask you to remember that Jesus said that when you see Him you see the Father). It is God Himself whose character it is to see goodness in others and live for the sake of others. So although we should indeed give all the glory to God, “Glory to God alone” does not mean that God does all things for His own glory, for I do not think this is the case. Indeed, I believe that God does all that He does for the sake of others also, and that all He does in His dealings with mankind is only for our benefit and not for His own aggrandizement.