Branch Davidians believe they are God's chosen people for the Last Days prior to the end of the world. Because of this they believe that God will always send a prophet to guide them. In this sense they keep to the original spirit of Seventh-day Adventism, where for the first 70 years of its history God was believed to send messages to the Church instructing it and guiding it. Branch Davidians have had five prophets: Ellen White, Victor Houteff, Ben Roden, Lois Roden and David Koresh (although not all of these were Branch Davidians, see the History of Branch Davidians). Currently the group still believe they are being sent messages from God.
Branch Davidians believe God is guiding his Church into more and more truth. They trace this back to the Reformation, with Martin Luther beginning this journey: he was succeeded by Knox, Wesley, Campbell, Miller, then the Seventh-day Adventists, then the Davidian Adventists and finally the Branch Davidians. The Branch Davidian view of Doctrine is therefore very dynamic and evolutionary - they are constantly expecting "New Light" to be shown by God to his/her people. The prophets are the means by which God reveals New Light, but this is always by drawing out the real meaning of texts from the Bible. Hence a prophet does not simply announce a new teaching, it always has to be shown to be what the Bible has taught all along, but people have been "blinded" to.
True Believers are not therefore those who are morally good - Branch Davidians believe that the Bible teaches that no one can be perfect - but those who believe "Present Truth" (the latest teachings from God). It is by constantly following the new teachings from God that the believer will be saved.
The Last Days
But why does God keep revealing New Light? Why didn't He just reveal himself in Jesus - as his Final Revelation to the world? The answer to this lies in prophecy in the Bible.
The Bible is full of prophecy. Right at creation God prophecies what will happen if Adam or Eve eat from the Tree of Knowledge (Gen 2:17), at the Fall he prophecies again (Gen 3:14-19), and this continues throughout the Old Testament - in the Law, in the Psalms and of course particularly in the Prophets. In the New Testament we constantly hear that Jesus acts "that it might be fulfilled" (e.g. Matt 2:17) - does this mean that all Old Testament prophecy is fulfilled in Jesus? No, because the New Testament also speaks of prophecy being fulfilled at the end of time - prior to the Second Coming (e.g. Matt 24, 2 Thess 2:3), and itself contains a complete book of prophecy - the Revelation of Jesus Christ, the last book of the Bible. Branch Davidians believe the Bible teaches that these prophecies referring to the Second Coming have been "sealed" or locked up, until the end time. It is because we are now in the end time that Branch Davidians believe God is now revealing him/her self again, and the mark of God's chosen people is that they have this new revelation from God. Thus the New Light is being given because we are in the end time, the New Light is God's final revelation to humanity.
The Seven Seals
Branch Davidians believe God has two revelations to humanity - one in Jesus Christ and one at the end of time. This corresponds to the "daily" sacrifices prescribed in the Old Testament, and the two sacrifices as part of the Day of Atonement. The identity of the lamb at the end of time can be established as the one who is able to "unlock" or explain the Seven Seals of Revelation (these are a series of mysterious prophecies in the Book of Revelation). Because David Koresh was able to explain the Seven Seals, Branch Davidians claim he must be the second Messiah. Therefore they claim the US Government has murdered the Son of God.
The explanation of the Seven Seals is not a particular message or secret, rather it is a way of re-understanding the whole of the Bible. The Seven Seals are a hermeneutic, a way of finally understanding what the whole Bible means. Thus for example Jesus claims to be speaking in parables to continue to hide the truth (Matt 13:35-36) whereas the Seven Seals finally reveal God's truth in the Bible. This is why Koresh's "Seven Seals" Bible study broadcast during the seige actually only goes into any detail on the first seal - he is showing how the first seal explains the Psalms. The principle is the same for the other seals, but in particular applies to the Seventh Seal, which is the most important re-interpretation.
The Branch Davidian Web site contains the latest re-understanding of the New Light, seen from beyond the Seven Seals.
Many people may be persuaded that the seals are worth investigation, but judge the Branch Davidians to be in error on the basis of David Koresh's behaviour - no one like that could be a Messiah.
A shown above, the saved are those who follow New Light, and this does not necessarily affect behaviour, however the Branch Davidians argue that truth comes from God, not the prophet or even the lamb. Jonah for example could never be said to be a good person - first he runs away from God, then he complains when those he was been teaching actually repent - yet God chose him and used him. Similarly the prophets themselves in the Old Testament exhibit bizarre behaviour, from marrying prostitutes to eating shit. One Branch Davidian document describes Koresh prior to his death as been "spiritually blinded" as Samson was prior to his death. It is also claimed that as part of God's second incarnation he should experience sin (as the "sinful sacrifice" in the Day of Atonement).
The point of all these arguments is that the teaching itself could be true, even whilst Koresh's behaviour was wrong.
The latest revelations from the Branch Davidian web site (also published in a book, Hidden Manna: Branch Davidian Revelations) claim that the 2300 day prophecy from Daniel 8:14 may apply from Koresh's death on 19th April 1993 - in other words around 6.5 years after, which takes us to around the year 2000, when a "cleansing" will take place.