I agree with everything except that if one does not produce fruit, they were never a child of God. God is the only one that truly knows peoples hearts. And i believe that anyone who asks, and receives by faith Jesus as their Lord and savior, they are truly saved. But the problem can be in the fact that the new believer is not developed enough in the Word to know if they are going to a good Bible believing church or not, and just like i have herd happen, people who are well meaning Christians, but not moving in the flow of the Holy Spirit, can quench a new believers fire, thus causing all kinds of things to happen. Giving lots of room for the enemy (as in the parable in mark 4) to come in and steal the Word.
It happened to me as well. I was saved, but because of how i was raised, (not on purpose, but carnally minded) and the mistakes or doors to God that i closed, caused me to be blinded to the reality of truly walking with God, according to His ways. I knew what the Word said, but because of my lack of understanding, and the fact that i didn't know how to not allow the devil to steal the Word, i backslid. As God moved me away from my old ways of thinking, and people who influenced those wrong ways, is where i learned to fully embrace God's ways of doing things and being right. I didn't even know and was never taught about the battle that goes on in the mind, and how to walk in victory.
Thanks for the opportunity to share my thoughts! Blessings my friend to you and yours!