This strongly suggests that those promoting error are guilty of blasphemy.
I do not understand why people get confused about the idea. A work of grace is just that. God blesses the evil and the righteous. Jesus is warning people not to fling around ideas based purely on what people feel is from God or not.
I have seen groups find real emotional reality in Jesus and go extreme and off the rails because they then rejected simple discipline and respect. Now some would say this was because they were deceived and lured away from the faith.
I would say living a life in love and the Spirit is life itself. The church has often had two halves, one applying the principles with intellectual honesty and the other responding to emotions and leading from the Spirit. Both are valid and both can fall into condemning the other as being the work of the enemy.
I have seen here conversations where people have condemned others in this very way, but when you look at the ideas it is a theological position someone has taken, with no apparent evil spirit involvement and probably a real work of grace in someones life.
Ananias and Sapphira lied to the Lord and died. People broke bread in a way that was wrong and died.
Churches has been shown a work of God, rebelled and ended up falling apart.
The Lord is Lord, and His warning needs to be taken seriously. It is always easy to say "I am with the Lord, so those who disagree with me are evil" when we are frail flawed people who are apt to get over enthusiastic about our ideas, and not be patient and loving with those who do not agree. In the extreme you end up like the pharisees from which there is no way back, if you reject the very works of grace He is doing. Some have already done this to me, when I have just shared how the Lord has blessed me.
My conclusion is if you cannot come like a child to works of grace you might find you are in a bad place.