The easiest way to test if an idea said in a church is not true, or at least not always true, is to see if you can find a counter example in scripture.
Often the narrative of scripture provides the best counter examples to ideas. There is a lot of scriptural narrative which has no comment. This is often seen as an objection to this approach.
The reality is a larger portion of narrative does have comments the are just rather subtle.
For example here is a common error and how it can be shown to be wrong: "God blessed the righteous and curses the wicked materially and physically."
This is sort of a crass version of the health and wealth gospel. If we simply look at the character of John the Baptist we will see the flaw of this system.
John the baptist lived a live of poverty and his life ended in prison when he was beheaded. But Jesus said that there was no one as righteous as John the Baptist.
You can also look at David and Saul where for a very long time the health and wealth gospel would give a completely wrong description of the situation.
Often with errors it is subtle they are half true. The statement in question is true in the world to come but not necessarily in this world.
Often half truths are more dangerous than full untruths. Full untruths are easier to notice and thus have more potential for damage.
A sort of "guess and check" version of theology has a lot of use. We should always test what we believe vs. the contents of scripture.
If what we believe doesn't match the bible then we will need to change the beliefs to match the content of God's word. I refer to this as "sitting under scripture" rather than "standing over scripture."
If it ever appears our beliefs counter scripture as Christians we need to seriously consider modifying our beliefs to be more closely in tune with God's word.