Does it trouble you to see those that you thought were mature Christians go off the deep end in one way or another?
“Yes. Is that because they never were Christians in the first place?”
Sometime, but not always.
“How else does it happen?”
Listen to one common way mentioned in Proverbs 19:27:
My son, stop listening to discipline and you will wander from the ways of knowledge.
One of the words that in Proverbs and Psalm 119 (and elsewhere) refer to Scripture is “discipline.” This designation comes from the fact that it is God’s truth that structures our lives in a disciplined way. Anyone who stops studying the Bible and attending the preaching of the Word will soon begin to think erroneously. We all need the regular nourishment that comes from an ever-increasing understanding and application of Scripture. Moreover, those who fail to be disciplined by God’s truth will “wander from the way” of God.
When a problem or decision arises, unless he knows what God has to say about it, he is almost certain to think wrongly and make bad decisions.”
“So the answer is to continue becoming more and more disciplined in those ways?”