As far as the Bible is concerned, it is clear that God has spoken with an audible voice before, and there is nothing to indicate that He might not do so again. Prophets in visions probably perceived God's voice at times as audible. Though I wouldn't assume they always did.
I listened too much of the conference but found it lacking in true Biblical teaching on the matter. The arguments seem to be based primarily on misinterpreting proof-text and also on extra biblical teachings about scripture.
For example, a certain spin on a post-Reformation doctrine of 'sufficiency of scripture' was used in opposition to actual Biblical teaching on spiritual gifts. I Corinthians 12 teaches that spiritual gifts are indeed given to individuals in the body of Christ, including prophecy, the word of knowledge, and the word of wisdom. That's the teaching of scripture. The idea that God speaks only (or nearly only) through scripture is not something the Bible actually teaches. Yet this is part of the Strange Fire spin on 'sufficiency.' The speakers relied on their extra-biblical (and unbiblical) doctrine of 'sufficiency of scripture' instead of believing what scripture actually teaches.
II Timothy 3 was also misapplied. In the first chapter, Paul tells Timothy to stir up a spiritual gift that was in him by the laying on of Paul's hands. If we accepted the Strange Fire teaching on I Timothy 3, would we have to conclude the Timothy's gift ceased before he had a chance to stir it up? What could he have done with that gift in the time it took to read three chapters?
II Timothy 3 reminds Timothy of two sources of revelation, the word he'd heard, and the written scriptures he grew up reading. That would have been the Old Testament, not a modern complete copy of the Bible.
II Timothy
14 But as for you, continue in what you have learned and have become convinced of, because you know those from whom you learned it,
15 and how from infancy you have known the Holy Scriptures, which are able to make you wise for salvation through faith in Christ Jesus.
16 All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness,
17 so that the servant of God may be thoroughly equipped for every good work.(NIV)/b]
Unless someone has an a priori prejudice against gifts of the Spirit, I don't see how he'd get some kind of cessationist doctrine out of this passage. This passage does NOT say that scripture is all that is given for the man of God to be thoroughly equipped. It's strange to me that some cessationists eisegete into the verse. It's a logical error.
If all scripture is given that the man of God may be fully equipped, that doesn't mean that all the man of God needs to be fully equipped is scripture.
Consider this logical analogy. The Roman soldier is given a short sword that he might be fully equipped. But take a group of naked soldiers and give them a sword and they won't be fully equipped, the fully armed soldier can be fully equipped if he is given a sword. The sword alone does not fully equip him. This is a good analogy since Philippians tells us that the sword of the spirit is the word of God.
Yet to be fully equipped, a man of God needs a number of things, including salvation, righteousness, faith, and a readiness to proclaim the Gospel of peace. All these things are taught on in the New Testament. We shouldn't read II Timothy 3 and say we don't need the things the Bible tells us are needed because we have the Bible. That's a convoluted interpretation.
Cessationist would not conclude:
"We don't need love because we have the Bible."
"We don't need faith because we have the Bible."
"We don't need to abstain from sexual immorality because we have the Bible."
"We don't need water baptism because we have the Bible."
Everyone would disagree with that. But why would one conclude the following:
"We don't need the spiritual gifts the Bible encourage us to desire because we have the Bible."
That is just as nonsensical of an interpretation of the passage. And Paul, in his discussion of spiritual gifts that cessationists find objectionable, teaches that one gifted member of the body should not say to another "I have no need of thee." So how can we say members of the body operating in the gifts are not necessary?
It's also pretty obvious that neither Paul as the writer nor Timothy as the reader would have interpreted this passage to mean that once the canon was completed, certain spiritual gifts were no longer needed. They both would have had Old Testament scriptures in mind. If II Timothy 3 teaches cessationism, then wouldn't the gift of prophecy have ceased then, rendering II Timothy 4 and the book of Revelation not prophetically inspired?
I Corinthians 1:7 is pretty good evidence that Paul believed spiritual gifts, including the ones he would discuss in I Corinthians, would continue until Christ returns.
I find it truly strange that cessationists so often say this. The actual verse doesn't even mention the scriptures as being what we need for life and godliness. It's a strange anachronistic interpretation to read that idea into the verse. Peter did not even have the complete New Testament canon. Neither did his readers. But they did have the message of the Gospel and the Spirit working in them, and they had everything they needed for life and godliness.
II Peter 1:3
His divine power has given us everything we need for a godly life through our knowledge of him who called us by his own glory and goodness.
This reminds me of the logical error of an argument from fear. Like the guy who went to the doctor and says, "The doctor says I have cancer. If I had cancer, that would be scary. So therefore I do not have cancer." His discomfort and fear over the idea of cancer have nothing to do with whether he has it.
If it is scary or uncomfortable to imagine yourself in a situation where two people claim to have contradictory words from God, that does not disprove the Biblical teaching that the Spirit gives gifts like prophecy and the word of knowledge and that God communicates through dreams and visions.
We all agree that some first century Christians operated in these gifts. It was potentially possible that someone could claim God wanted one thing, and for someone else to argue that God wanted another. People still debate whether it was God's will for Paul to go to Jerusalem because of the brethren who warned him 'through the spirit' or 'through the Spirit'. The Thessalonians had probably heard some wacko end time’s teachings or prophecies. Yet Paul told them not to despise prophesying’s.
The face that two people could claim to receive conflicting revelation does not mean that no Christians in the first century received genuine revelation. If God put early Christians in a situation where they actually had to develop a kind of spiritual maturity and reliance on Him to discern who really had heard Him is it so outlandish to think that He would do the same for us? In some ways, we may have an advantage over some believers, especially those living far from the apostles, because we have the Bible.
The least among us shall be the greatest of all. And the one who prophesies is greater than the one who speaks in tongues, unless he interprets, that the church may be edified.
And Jesus referred to casting out demons as a miracle. If miracles were withdrawn, then no one would be able to cast out demons. Why would God leave the demons roaming around with all kinds of power, but withdraw the power that the New Testament teaches that He has given to the church? I don't see how such an idea is consistent at all with the teaching of the New Testament on the issue.