How do you react to ideas being introduced by other religious groups? (Part 1 of 3)

How do you react to ideas b
This is what I understand from this Brother Eli's video:
https://3speak.tv/watch?v=fatimajunio/earmohfh
One of the ways to prove whether a prophet is of God is to analyze what he says, to know whether his statements are true.

We can use the advice of Deut. 18:22 which states that if a prophet pronounces what did not come to pass, such a prophet is not from God. It says we should not fear a prophet that speaks presumptuously, that's who is proudly saying what God has not said.

Based on that, we can find out like Bro. Eli personally found out that Joseph Smith was a false prophet. This is so, because Joseph Smith made a wild claim in the name of a revelation from Jesus Christ where he claimed that the New Jerusalem shall be built in the western boundaries of the State of Missouri. He also claimed that he, with others will dedicate the building of the city. He said this was the word of the Lord concerning his Church.