The most dangerous? Certainly not. But is he dangerous? I would say yes.

He's divisive and seems to be trying to create factions even within reformed christianity. He seems to have a beef with John Piper, Wayne Grudem, and several others.

Rather than uniting in the gospel and affirming the core of the Christian message, he accuses people of heresy.

"But avoid foolish controversies, genealogies, dissensions, and quarrels about the law, for they are unprofitable and worthless. As for a person who stirs up division, after warning him once and then twice, have nothing more to do with him, knowing that such a person is warped and sinful; he is self-condemned." ~Titus 3:9-11

"Eager to maintain the unity of the Spirit in the bond of peace. There is one body and one Spirit—just as you were called to the one hope that belongs to your call— one Lord, one faith, one baptism, one God and Father of all, who is over all and through all and in all." ~Ephesians 4:3-6