There's something that worries me about some emerging church types.
They don't all do it, but many do. It's seems pretty popular of late to talk about how "our" orthodoxy is simply the philosophy that won out, and that we should continue to look at "minority" positions (i.e., heresies). To these folks, the differences between the orthodox and Arians (and maybe gnostics) are no different than those between protestants and Roman Catholics or even Baptists and Church of Christ.
In their search for "humble" orthodoxy they seem willing to give up too much ground. Our spiritual ancestors fought long and hard to develop and preserve doctrines that are consistent with the biblical data as well as philosophically/logically sound.
While I do want to us read the old heresies, we have to keep in mind that they are heresies. It is altogether too easy to fall into heresy, and as we move further away from the truth, the lies become more dangerous.
Here's an example. If we give up the deity of Christ the atonement no longer makes sense – it looks like "divine child abuse." So to save God, we have to give up the atonement. The cross becomes meaningless.
So what do we do about the cross? The usual response is that God didn't know Christ would die and/or didn't save Him – meaning God doesn't know the future and can't or won't stop evil from happening to His own son.
The next step, of course, says since there is no atonement, there'd better be no sin – or at least no punishment for it. So we have a "nice" God who is not just and is simply trying to keep the world from falling apart as we race along screwing stuff up.
This is a reasonable, natural progression from giving up the deity of Christ to a mishmash of open theology and antinomianism (i.e., it doesn't matter how you live). Not only is this not a God I'd want to worship, it's a religion that has nothing to offer.
I'd like to recommend this piece from Scriptorium Daily on the Council of Chalcedon and this personal story of the dangers of leaving orthodoxy at Crossroads.