Greta Thunberg isn't the worst theologian I can think of.
The "Baptist" theologian that says the gospel requires net zero emissions is worse.
The "Anglican" theologian that says SSMs are legitimate in God's eyes is worse.
The "Charistmatic" which plants a person in a crowd to fake a healing is worse.
The "high-Church" theologian that tells women the woman being sent to grab the disciples means she was a preacher is worse.
The prominent Church that uses its donations for a lavish lifestyle for its pastors is worse.
Because they should all know better. Their increased training increases their responsibility and culpibility for such lies.
I use quotes around the denominations because you could interchange them with examples across the board.
Oh, and the charlatans that gave Greta her honourary doctorate, aren't that crash hot either.