Best advice of all - Read the Scriptures, know the scriptures, and follow what the LORD teaches in His holy scriptures!
Also, Hebrews 10 has a similar warning to all who come close to Christ (have received a knowledge of the truth.) It is not 100% clear if these had become what we like to label as "Christians," but they did attain a level of knowledge of God's Truth that left them without excuse. They would have made certain progress in coming to Christ, and then, turned their backs, walked under foot the good things revealed to them and done for them by God, and done all this despite the clear understanding of a benefit they already received in seeking the LORD.
Hebrews 6
4 For it is impossible for those who were once enlightened, and have tasted of the heavenly gift, and were made partakers of the Holy Ghost,
5 And have tasted the good word of God, and the powers of the world to come,
6 If they shall fall away, to renew them again unto repentance; seeing they crucify to themselves the Son of God afresh, and put him to an open shame.
7 For the earth which drinketh in the rain that cometh oft upon it, and bringeth forth herbs meet for them by whom it is dressed, receiveth blessing from God:
8 But that which beareth thorns and briers is rejected, and is nigh unto cursing; whose end is to be burned.
Hebrews 10
26 For if we sin wilfully after that we have received the knowledge of the truth, there remaineth no more sacrifice for sins,
27 But a certain fearful looking for of judgment and fiery indignation, which shall devour the adversaries.
28 He that despised Moses' law died without mercy under two or three witnesses:
29 Of how much sorer punishment, suppose ye, shall he be thought worthy, who hath trodden under foot the Son of God, and hath counted the blood of the covenant, wherewith he was sanctified, an unholy thing, and hath done despite unto the Spirit of grace?
30 For we know him that hath said, Vengeance belongeth unto me, I will recompense, saith the Lord. And again, The Lord shall judge his people.
31 It is a fearful thing to fall into the hands of the living God.
We can devise a statement that displays what we have decided is a principle of God's truth, but it must match what scripture states for it to have any usefulness.
One good sermon I heard 30 years ago stated that there are 8 things God does in saving a soul. He listed them and expounded upon each alphabetically.
1- Adoption
2- Atonement
3- Conversion
4- Forgiveness
5- Justification
6- Reconciliation
7- Redemption
8- Regeneration
I had not considered this as a truly saved person changing to follow self, sin and the devil. If we get some of what God does to bring a sinner to Him, and turn away, we may not actually have been what is categorized as SAVED, but have gone far enough with God where there is no returning. It is a fearful thing indeed to put ourselves in this position and then face the living God with our rebellion. It is a double rejection of the LORD.
The real problem comes when Churches (of any stripe) think they are to assure someone they are "SAVED" outside the full assurance and pure sense given to them by God's Holy Spirit. Churches have criteria, and if you do certain things, or say certain things, you are SAVED. Then, they need to come up with explanations like this, and doctrines to cover things they don't see handled that way in scripture.
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