Yes are all defective and it was stated that there are some denominations the suffer defects in I suppose in theological areas.
So if those denominations suffer defects in their teachings and beliefs then the followers would also suffer defects in their beliefs and understandings.
Well…let me put it this way…if you were taught 2+2=5…then you would carry this through your whole life as true…2+2=5. You would not know any better…until someone can convince you it is false. You would stick to your belief that 2+2=5 like a leech.
And if the denomination’s teachings came from the rejection of apostolic authority…1 Samuel 15:22-23
22 But Samuel replied:
“Does the Lord delight in burnt offerings and sacrifices
as much as in obeying the Lord?
To obey is better than sacrifice,
and to heed is better than the fat of rams.
23 For rebellion is like the sin of divination,
and arrogance like the evil of idolatry.
Because you have rejected the word of the Lord,
he has rejected you as king.”
And it is for this very reason the Bible says:
Then from 1John 4… Dear friends, do not believe every spirit, but test the spirits to see whether they are from God, because many false prophets have gone out into the world……………6 We are from God, and whoever knows God listens to us; but whoever is not from God does not listen to us. This is how we recognize the Spirit[a] of truth and the spirit of falsehood.
And you can see the revelation to Paul to find out what the truth is:
Galatians 2:2 I went in response to a revelation and, meeting privately with those esteemed as leaders, I presented to them the gospel that I preach among the Gentiles. I wanted to be sure I was not running and had not been running my race in vain.