Hi,
I do believe all John says.

We just disagree on the Eucharist and of course our definition oof the church is different as well…

Other than that Im with you on everything else you mentioned.

One of my friend’s grew up in a SDA church and she admits they have some whacky views which is why she left. She did they though that they also taught the truth about Jesus Christ and who he was.
How in the world can any sensible person make the statement
“I agree with everything St. John wrote in his Gospel except the part on the Eucharist?” This is nonsense.
That is like saying you believe everything about Jesus except the level of pain he endured on the Cross. How would you know?
John was the beloved disciple, John was there, John understands the Eucharist fully. without John, our understanding of the Eucharist might very well be a dead thing which is why he was after some reluctance included in the Canon. I say reluctance because John was heavily theological whereas the other three were practical and narrative in style. so to say you use the Bible as your authority and you agree with John on everything except the Eucharist?
The SDA is only an example of the evils inherently associated with personal Bible interpretation outside of the Church.
SDA’s are Bible literalists and sola scriptura. They will interpret the Bible as they see fit. The ironic thing is their favorite Gospels
is John. Yet, John, in his day in Emmaus, was the biggest enemy of their forerunners- the Manacheans. Anyone who has studied Manacheanism and Seventh day Adventists know they are one and the same with some Baptist and Calvin thrown in.
My point though was not to talk about SDA’s.
My point to you is that all Protestant religions can find their counterpart in the first 400 years of Christianity when the Gospel writers, John, Mark, Matthew, and Luke and then the Church Fathers were attempting to combat their heresies.
The heresies came from one or two passages in a Gospel or the Old Testament that the interpreters took off and ran with.
It is ludicrous to claim your religion has truth due to Bible knowledge if your religion is one of the heresies combated and refuted by the Apostles and those who wrote the Gospel in the first place as in the case of John.
It does not matter if the name changed. Dualism, manacheanism, and gnosticism and arianism- they are all alive and well and the foundational theology of churches such as the SDA and Calvin’s Churches.
In effect these religions are arguing with the Gospel writers while holding up the Gospel writers as the only truth. Yu cannot hold up something as absolute truth if you are disagreeing with the guy who told it to you in the first place!
Ridiculous but it only occurs due to free lance Bible interpretation.