"Truth Matters 2013: Strange fire" conference" - What does the biblical term "strange fire" signify about the Charismatic movement?

You refer to "the first "Strange fire Conference" launched in October 2013" and a new book by John MacArthur on the dangers of "strange fire". That reminded me of a book about strange fire which I read way back in the late 1990s. It's called, "Strange Fire? - assessing the Vineyard movement and the Toronto blessing" by Eric E. Wright and was published by Evangelical Press in 1996. It examined events from the 1980s onwards. I've just pulled it out to use by way of an answer.

The author attended some meetings in 1994 in Canada at Airport Vineyard Christian Fellowship. Around 700,000 people visited and went night after night to their meetings between 1994 and 1996. Apart from people in Canada and many US states, folk had come from Britain, Norway, Germany, Australia, Bermuda and Nicaragua. Vineyard leaders believed there was an outpouring of the Holy Spirit happening and said this was evidence of what they called 'power evangelism' through a revival of signs and wonders. Speakers said God was wooing them from their denominational preoccupations to go deeper into the Spirit, and that the manifestations of what they called 'being slain in the Spirit' sometimes led to being anointed for ministry, hearing the voice of God, receiving visionary revelations or the ability to prophesy. People were urged to take 'the blessing' back to their home church. Many meetings would go on into the early hours.

Supporters of that movement, and all other similar ones since, would say that spiritual revival and renewal was breaking out, and that this is seen by them as "Third Wave Pentecostalism". (Pages 15 to 23 of Wright's book.)

The answer to your first bullet-point question is that Charismatic people know what the Bible says in Leviticus about the 'strange fire' offered by Nadab and Abihu, with God striking them dead, and they are very hurt that non-Charismatic Christians (like Wright and MacArthur) claim modern-day Charismatics are offering 'strange fire' as worship. They deny that, and insist the strange events manifested in their worship gatherings are proof that God's Holy Spirit is using them to bring revival. As one example of how they see things, here's a quote from some Kansas City prophets:

"Along with James Ryle and Wes Campbell, [prophets] have brought prophecies predicting a future war between two groups of Christians - the 'blue coats [those who believe in ongoing revelation] and the grey coats [those evangelicals who are stuck in a theological time-warp infected by the wisdom of the world]'...

Campbell's wife, Stacey, came up to predict a great division in the church. She foresaw a time when Vineyard adherents would be accused of being cultic... Wes Campbell concluded his prophecy by warning, 'Do not allow your ears, do not allow your hearts to be turned to those that would say unto you, 'Be reasonable! Be rational! This is not logical!' I say unto you, the natural man receiveth not the things of the Spirit of God, for they are foolishness to him." (CRI transcripts of Wes Campbell, Toronto Airport Vineyard, Oct. 14, 1994, pp.84, 86, 88, as in Wright's book, pp 138-4)

Your second bullet point question, "What is the Biblical basis for the calling of the Charismatic movement as Strange Fire?" cannot possibly be given a decent answer here. Wright wrote a 325 page book explaining that very question and I daresay MacArthur's book would be of similar extent and substance. After reading one or both of those books, a biblical answer would be clear, and people could make up their own minds. The scope of that second question is too vast to do justice to here. Sound-bite answers just will not do.

Jesus warned of false prophets arising, who would claim to do many miracles in Jesus' name, but whom he would disown as not having done the will of God (Mat.7:21-23). Interestingly, he did not say 'all' such miracles would be false but he did said that, "By their fruits you will know them" (verse 20). There has been enough time now to examine the 'fruits' of that Charismatic movement, to see how many prophecies were either just false, or attempts to interpret the will of God according to their theology, and how many claimed miracles were not miracles at all. There is also the test of love - for those who expect a 'war' between two groups of evangelicals, whether that's a self-fulfilling prophecy, or, indeed, a sign of cultic exclusivity and control techniques to keep people in.

The question asks what it implies to the Charismatic movement, but the topic of "strange fire" applies to any natural initiative outside the commandment and anointing of the Lord.

Then Nadab and Abihu, the sons of Aaron, each took his censer and put fire in it, put incense on it, and offered profane fire before the Lord, which he had not commanded them." (emphasis mine) Lev 10:1

The Lord gave instructions on how to operate the tabernacle. That principle is still in place in the church age's appointment of offices, ministries, etc.

Back up to the prior chapter, Lev 9:24

Fire came out from the presence of the LORD

The fire was supernatural. Nadab and Abihu took it upon themselves to light the censer with a natural source of fire. The principle is the Lord anoints, appoints, and provides the initiative/energy. And any other source is not acceptable.

A NT verse of the same natural initiative principle:

Not everyone who says to Me, ‘Lord, Lord,’ shall enter the kingdom of heaven, but he who does the will of My Father in heaven. Many will say to Me in that day, ‘Lord, Lord, have we not prophesied in Your name, cast out demons in Your name, and done many wonders in Your name?’ And then I will declare to them, ‘I never knew you; depart from Me, you who practice lawlessness!’ (Matt 7:22-24)

'Lawlessness' isn't breaking the ten commandments in this context. Rather, it is any work of ministry outside the direct appointing and anointing by the Lord.

Just because someone takes it upon themselves to do acts of worship or service in the name of the Lord doesn't mean the Lord authorizes it or anoints it. Nobody chooses their own place or role in the body:

God has set the members, each one of them, in the body just as He pleased. (1 Cor 12:18)

He will choose our inheritance for us (Ps 47:4)

The same principle is true for keeping the Lord's Sabbaths: we are vessels and the Lord does the work in us:

For You have also done all our works in us. (Isa 26:12)

The natural man works by his/her own effort rather than yielding to the Holy Spirit's direction. Nothing of the natural will, mind, or emotions is acceptable to the Lord. (Rather it is the very thing the Lord is seeking to deliver us from, see 2 Peter 1-4).

Charismatics are often associated with very dramatic worship services. Mature spiritual discernment will realize much of it is of the natural man. But, so are a lot of non-Charismatic services. Entire ministries are in abundance of little more than the natural man.