I learned those things from studying the Bible and from studying the teachings of some of the world’s false religions. When you study the Bible in-depth, you learn many things, with the Holy Spirit as your teacher, and you can easily spot counterfeit teachings.
Doctrines of Mormonism, Catholicism, Islam, and other world religions are contrary to the Bible’s teachings. Unless you see the Word of God for what it is—God’s Word—then none of this means anything to you anyway. The Bible warns against false religions in both testaments. The apostles warned of fakers who were infiltrating the church and leading people astray.
If you knew the Word, you would know that it lets us know that Satan is the great deceiver. Read the book of Revelation, as I mentioned earlier, there are plenty of passages just there alone that indicate he is a liar (Jesus also said he was a murderer and a liar from the beginning. John 8:44), and that all the nations of the earth will be deceived by him.
There are a number of places in the Bible, Old and New Testaments, that indicate only a remnant of humanity will be saved. Don’t you recall Jesus’ teaching about the narrow and the wide gates? Wide is the path and broad is the gate that leads to destruction and many go there, but narrow is the gate that leads to life, and few find it.
Read the Bible. It’s all in there, and much more besides.
So God so loved the world He sent a Book?
Read the Bible - great advice! Since you do read the Bible and believe what you read ( as we all should ) that means when Jesus said “This is My Body”, you believe he meant it’s His Body, correct? I am sure you will say correct, unlike a lot of people who claim to read and believe the Bible, but really don’t!