Comparing beliefs and theology to Scripture = objective. There is simply not that much serious differences in beliefs.
Sure people like Koresh and Jones can CLAIM the Holy Spirit, but a cursory look at their doctrines and teaching show deviation from that. They went wrong because they deviated from Scripture. There is that part about *Thou shalt not kill* and *Thou shalt not commit adultery* which they ignored.
It's obvious to anyone, that despite their claims of being led by the Spirit, that they weren't and their followers would have recognized it if they had investigated Scripture instead of putting their faith in their leaders.
That is certainly the way Jesus advised us how to know if someone was from the Lord. "By their fruits ye shall know them." All those people who followed after those charlatans - and they were NOT the first nor the last ones to exist - were spiritually blinded either by their own sinfulness, laziness, greed and who knows what else. The same kind of attitude is all around today right out in the open and some brazenly so. Look at the Westboro loonies. Scripture MUST be the authority for faith and life and its truths are just as relevant today as they were thousands of years ago - human nature doesn't change. The Apostles and the early church believers battled apostasy and heresy back then, too, and their sword was the Word of God and their shield was faith. It IS a spiritual battle, after all.