He says Jesus WAS the mushroom, he is positioning it as if entheogenic cults are worshipping the plant spirits and the actual earthly events in the past are inconsequential and just mythology.
That is an anti-Christian heresy and should be condemned.
It may be possible that entheogenic sacraments have been used in past times, however, the fullness of any experience is only made possible through the birth, life, and death of Jesus Christ on Earth. If it was not for Jesus Christ and his true earthly incarnation, then it would not be possible for man to experience the fullness of God. Jesus Christ came to save us.
Texts similar to Allegro’s book, The Sacred Mushroom and the Cross, seek to bring validity to the consumption of plant medicines by associating them with religious tradition.
Jesus Christ was fully man, and fully God. He was not a mushroom.