When you have had an encounter with God, people can talk and say whatever they want but you’ll never doubt God.
John 4:42 Then they said to the woman, “Now we believe, not just because of what you told us, but because we have heard him ourselves. Now we know that he is indeed the Savior of the world.”
Christians knows the scriptures, they have heard a lot of preaching, what is missing is an experience with God. The Word must become alive in them and bring transformation.