We find out in Mark chapter 3:22-30.
And the teachers of the law who came down from Jerusalem said, "He is possessed by Beelzebub! By the prince of demons he is driving out demons."So Jesus talks about people "blaspheming against the Holy Spirit" in the context of the teachers of the law saying that things done in the power of God were actually done in the power of Satan. They should have been able to recognise the power of God to work for good - but they deliberately chose to interpret it as satanic power. Blasphemy against the Holy Spirit isn't something you can do by mistake. It's not something you can casually do. It is about being close enough to God to see him working - but then interpreting his work as being evil rather than good.
So Jesus called them and spoke to them in parables: "How can Satan drive out Satan? If a kingdom is divided against itself, that kingdom cannot stand. If a house is divided against itself, that house cannot stand. And if Satan opposes himself and is divided, he cannot stand; his end has come. In fact, no one can enter a strong man's house and carry off his possessions unless he first ties up the strong man. Then he can rob his house. I tell you the truth, all the sins and blasphemies of men will be forgiven them. But whoever blasphemes against the Holy Spirit will never be forgiven; he is guilty of an eternal sin."
He said this because they were saying, "He has an evil spirit."(NIV)
The closest comparable situation I've come across in my own experience is somebody who is convinced that the assurance some other people have of their salvation (which the Bible says comes from God) was actually satanic - when the evidence in those people's lives was also clearly that God was at work in them.
I mention this having come across this website. Some thoughts.
Firstly, you can't decide anybody's eternal destiny, not even your own. Only God can do that. Whilst taking part in the activities described on the website hardly constitute a healthy spiritual discipline, I don't believe they have "binding value" as far as God is concerned.
Secondly, I doubt that there are many people sending in videos who have been in a position to see what God's work is like - certainly not in the same clear, unambiguous way that the teachers of the law had when they said that Jesus was working in the power of Beelzebub. I suspect that you can't blaspheme against the Holy Spirit unless you know what the Holy Spirit's work is like, and I doubt that most of these people do.
Finally, that notwithstanding, provoking people to damn themselves is very serious. Not for the people provoked, but for the provokers.
1Jesus said to his disciples: "Things that cause people to sin are bound to come, but woe to that person through whom they come. It would be better for him to be thrown into the sea with a millstone tied around his neck than for him to cause one of these little ones to sin. So watch yourselves. Luke 17:1-3 (NIV)The people who put together the website are in greater need of prayer than the people who send in a video.
I'm slightly surprised that Pascal's Wager doesn't have more impact. I suppose that shows how much confidence people have that there is no God. Which is odd, given the large proportion of people who think that there is a God.
(I feel honour-bound to point out that David Heddle has a post with the same title, that makes similar points - though almost certainly more thoughtfully and accurately. However, since most of my hits at the moment are coming through the link to my post that he included in his, this is perhaps hardly necessary!)