The idea that Jesus is more than a man, but not exactly God, is hinted at in some (false) presentations of Catholic and Protestant teaching. When I led the “Liturgy of the Word for Children”, the text urged prayers “to God, to Jesus, and to the spirit”. I changed that of course to God the Father, Jesus (God the Son), and God the Holy Spirit, but others would read it the way the liberals wrote it.
Many religion texts, and other seminars or Bible studies, imply Jesus was conceived the way we all were. The message is that Jesus growing up had no idea he was God; but as he became more aware of himself, and concern for others, the spark of divinity potential in him (and in everyone) became fulfilled. The only miracle he performed was the Sermon on the Mount. His “resurrection” only means that when we become aware of our divinity, and nurture it in others, Jesus still “lives”.
The explicit Arianism of modern cults is less dangerous than the implied Arianism intentionally or unintentionally presented in Catholic and Protestant writings, lectures, etc. If you write “Jesus (or the Spirit) are not divine persons” you won’t get an Imprimatur or get invited to speak at renewal programs. But if you overemphasize certain things, and omit other crucial facts, people can be led to a kind of watered down Arianism without realizing it.