1. Scripture is authoritative as originally given.
Translations which distort the original meaning of the text do not carry God's authority. Now clearly it is not practicable, possible or necessary for all of us to learn Hebrew or Greek, but at least if in doubt we should be referring to commentaries which are based on the original language rather than an English translation. An example of an incorrect translation which has misled people over medical ethics is Exodus 21:22-25 dealing with the situation where two men are fighting and in the process injure a pregnant woman. The text has been used for decades to support the view that life before birth is of less value than life after birth. If you read the passage in both the AV and the NIV the meaning seems quite different and in order to resolve the difficulty we need to go back to the original Hebrew and ask what it originally said. This text was also mistranslated in the Septuagint, the Greek Old Testament and this led to centuries of misunderstanding and false teaching.
2.Scripture is authoritative in all that it affirms.
In narrative passages of Scripture there are things that the Bible records people doing and yet doesn't affirm. We don't emulate every thought, word and action of biblical characters (even 'righteous' characters) just because they are reporting as happening once. For example people have used biblical narrative to justify laying fleeces and drawing lots whenever they cannot make up their minds. While Jesus himself did appeal to narrative to justify his disciples behaviour (as in the case of David's eating bread on the Sabbath), he didn't similarly appeal to David' census-taking or adultery as a precedent. These actions were not affirmed. If something seems right but is neither affirmed nor denounced in the passage in question, then we need to look at narrative and didactic passages elsewhere in Scripture.
3. Scriptural truth is sufficient but not exhaustive.
It is sufficient to make us 'thoroughly equipped for every good work' but that doesn't mean that it will satisfy every idle curiosity we may have. It doesn't, for example tell us whether there is life on other planets probably because this is not relevant to our own salvation history. God tells us things on a need to know basis. There are secret and revealed things (Dt 29:29) The challenge is having the wisdom to know the difference. God's word is there to train us to distinguish good from evil (Heb 5:14) but we should know our limits, and while not pretending to know everything, we should nonetheless live up to the truth that we have attained (Phil 3:15,16) and err on the side of caution about what we are not sure of (Rom 14:22,23).
4. Scriptural truth is objective not subjective.
It doesn't mean different things for different Christians. We can't say that this text means one thing for me and quite another thing for you. For example it is not okay for you to perform euthanasia but it is admissible for me. That's relativism! The Bible's author and not its reader determines the meaning. In saying this we are not saying that the Bible cannot have any meaning that was not in the minds of the human authors. It is quite clear that in many passages of Scripture God had intentions in the text which were not known to the human authors but nonetheless present. For example Paul justifiably applies a text about not muzzling oxen in the Old Testament (Dt 25:4) to the support of Christian workers in the New Testament (1 Tim 5:18). Similarly in saying that it was expedient for one man to die for the nation, Caiaphas was not intending to be prophesying in John 11:49-53 that Jesus death would pay the price for our sins, but he most certainly was!
5. Scripture does need to be understood in its historical and textual context.
Some commands in Scripture apply only to certain individuals and groups. A text without a context can be simply a pretext! This is particularly relevant to the use of the Old Testament, in particular the Law and the Prophets. We are not for example expected to eat kosher food as Christians nor to participate in animal sacrifice, although these were part of the Old Testament Law. We rather see the Old Testament Law as having the function of leading us to Christ. Animal sacrifices under the Old Covenant point to Christ's sacrifice of himself for our sins under the New Covenant. Similarly the food laws were a reminder of God's holiness but are not binding on us as Christians. As Jesus said, it is not what goes into us, but rather what comes out of us that reveals where we stand with God.
On the other hand we can not disregard the Old Testament Law either. We can disregard it as a means of gaining God's approval because we are under a new covenant where right standing before God comes by faith. But as instruction in right living the law is still of great benefit. When Paul said in 2 Timothy 2:16,17 that all Scripture is inspired by God and useful for teaching rebuking, correcting and training in righteousness, he was referring primarily to the Old Testament.
Some Christians here get obsessional about the question of which parts of the Old Testament Law are then still binding on us, but this is the wrong question to be asking. The Bible does not divide the law into moral and ceremonial parts and say that the former (but not the latter) are still binding on us. Nor does it say that all law not specifically abrogated in the New Testament still holds, nor that all that isn't reaffirmed there is obsolete.
It says rather that we are not under law, but rather under Christ's law (1 Cor 9:20-21). We are to love one another as he has loved us (Jn 13:34-35), to bear one another's burdens (Gal 6:2). We must walk as he walked in the path of the cross (1 Jn 2:6; Mt 10:38). Faith expressing itself through love is the only thing that counts (Gal 5:6).
Some have used this as a starting point to justify situation ethics. This approach popularised by Joseph Fletcher argues that the breaking of biblical law can be at times justified in the name of love. However, Jesus would never have attempted to justify murder, adultery, theft or lying in extenuating circumstances, and neither should we. Love and obedience are inextricably linked in the mind of God.