I like Rupert Sheldrake a lot when he stays in his lane (biology and science), but he’s off when he’s talking about baptism here. There’s no reason to think John the Baptist held people under longer than what was normal for full ritual immersion in the Hebrew tradition. John was a rather popular rabble-rouser, and baptized a truckload of folks from all over. If all of them were being baptized in an unusual way, and, presumably, some of them were having a NDE (near death experience), it’s a “big and weird” enough occurrence that one of the writers of scripture would have mentioned it.
It didn’t seem like Rupert was totally serious about it, so I don’t hold it fully against him. Besides, out of any practice contemporary to John, adult male circumcision was the more likely candidate for an NDE.
Commenter gmdinformation has a similar view:
I usually agree with you Mr. Sheldrake, but there are some things about this notion of a drowning-baptism that come up short for me. Many people who drown do not simply take a gulp of water into their lings and pass out first. There is often a spastic reflex in their throat that causes it to seal off anything at all, so they have a horrific death of not being able to get a breathe. Various biblical prophets portray God as having said that worshipers of Ba’al were evil for making their children “pass through the fire.” I would think he would think it equally evil to have children or adults either one asphyxiate through a purposeful drowning. It’s also commonly thought that Christ asphyxiated on the cross and that this is why the disciples later made it a rule among their followers that they should not eat “the meat of strangled animals.” That doesn’t sound like a people group who would consider purposeful drowning to be something God would approve of.