Jesus answered and said to them, “You are mistaken, not knowing the Scriptures nor the power of God.” Matt 22:29
A group of Sadducee’s approached Jesus with a question about the resurrection, which they did not believe in.
They presented their question and Jesus presented the answer starting with today’s scripture – a slap in the face on their belief.
I do not know who started the sect of the Sadducee’s. I understand they refused to move beyond the Torah, the first five books of the O. T., that is, the Books of Moses. As a result of not accepting the other books of the O.T., they did not believe in the immortality of the soul, bodily resurrection after death, and the existence of angelic spirits.
Picking and choosing what to read and believe from the Bible is still an issue today. This is one of the reasons so many Christian denominations exist.
I am not going to claim that my beliefs are all the right answers to your questions. I have rejected many things taught to me in former churches. These things I see as useless traditions that deny the power of God.
Everyone needs a teacher but if that teacher teaches the wrong things, does that make it right?
It is written, for though by this time you ought to be teachers, you need someone to teach you again the first principles of the oracles of God; and you have come to need milk and not solid food. Heb 5:12
When it comes down to it, we need to get back to the basics of the Bible and examine what the word of God says compared to what our teachers teach.