How answereth ye? Can a person depart or not?

Take heed, brethren, lest there be in any of you an evil heart of unbelief, in departing from the living God. [13] But exhort one another daily, while it is called To day; lest any of you be hardened through the deceitfulness of sin. Hebrews 3:12-13

Again, When a righteous man doth turn from his righteousness, and commit iniquity, and I lay a stumblingblock before him, he shall die: because thou hast not given him warning, he shall die in his sin, and his righteousness which he hath done shall not be remembered; but his blood will I require at thine hand. [21] Nevertheless if thou warn the righteous man , that the righteous sin not, and he doth not sin, he shall surely live, because he is warned; also thou hast delivered thy soul. Ezekiel 3:20-21

Can a brother in the Lord depart from God?

Can a righteous man turn from righteousness and die in his sin?

As per the writer of Hebrews and Ezekiel the answer to these questions is ‘yes’.

It should be well understood that 'righteous' and brethen’ as used in Ezekiel and Hebrews are synonymous with 'saved'.

Hebrews 3:12 was definitely referring to ‘saved’ brethren. We see this as these brethren were referred to as ‘holy brethren’ further up in verse one of the same chapter.

In Ezekiel chapter three verses 20 and 21 the ‘righteous’ are being addressed. The preceding verses address the same issue, iniquity and dying from it, but in those God is addressing the lost, the ‘wicked’ (see verses 18 and 19). The context is clear that two groups of people are being addressed here and that ‘righteous’ refers to saved.

Righteous as defined by Webster’s 1828 dictionary:

RIGHTEOUS, adjective ri'chus.

1. Just; accordant to the divine law. Applied to persons, it denotes one who is holy in heart, and observant of the divine commands in practice; as a righteous man. Applied to things, it denotes consonant to the divine will or to justice; as a righteous act. It is used chiefly in theology, and applied to God, to his testimonies and to his saints.

The righteous in Scripture, denote the servants of God, the saints.

With this said, it is no wonder the church today looks no different than the world. It makes excuses in regards to sin instead (Grace covers all sin, including the present and future,  etc) of warning sinners, who think they can continue on in sin under today’s false modern doctrinal pretenses, that they are still saved. The church instead insists that the unrepented sinner is still saved. They insist this is so even though in reality the sinner is serving two masters...

This happens so much today that many claim to be Christian yet in reality it's the "few there be"...

People fight adamantly and sometimes with much anger to defend this false gospel as they refuse to accept what the Bible outright says about this to the contrary. If only they would put that same energy towards the truth and actually exhort people away from sin, warning the formerly righteous that they can and will die in their sin unless they "sin not".

The church today is busy assuring the lost, those who think they are saved, by telling them that they are OK. They should be exhorting these sinners in order to save their souls from eternal death.

Exhort as defined by Webster’s 1828 dictionary:

EXHORT', verb transitive egzhort'. [Latin exhortor; ex and hortor, to encourage, to embolden, to cheer, to advise. The primary sense seems to be to excite or to give strength, spirit or courage.]

1. To incite by words or advice; to animate or urge by arguments to a good deed or to any laudable conduct or course of action.

I exhort you to be of good cheer. Acts 27:22.

Young men also exhort to be sober minded.

EXHORT servants to be obedient to their masters. Titus 2:6.

2. To advise; to warn; to caution.

3. To incite or stimulate to exertion.

EXHORT', verb intransitive To deliver exhortation; to use words or arguments to incite to good deeds.

And with many other words did he testify and exhort Acts 2:40.

Disclaimer, this is not a "works based" salvation as only the death of Jesus Christ, the sinless, spotless, perfect Lamb of God can attone for sins. This sacrifice is not for those who reject it,  even if they had accepted it one time or not. The gift is for anyone would accept it and walk in it.

Seek the old paths and do not make any provision for the flesh (sin) for yourself or others!

Warn them!

They have healed also the hurt [of the daughter ] of my people slightly, saying, Peace, peace; when there is no peace. Were they ashamed when they had committed abomination? nay, they were not at all ashamed, neither could they blush: therefore they shall fall among them that fall: at the time that I visit them they shall be cast down, saith the LORD. Thus saith the LORD, Stand ye in the ways, and see, and ask for the old paths, where is the good way, and walk therein, and ye shall find rest for your souls. But they said, We will not walk therein. Also I set watchmen over you, saying, Hearken to the sound of the trumpet. But they said, We will not hearken. Jeremiah 6:14-17

The night is far spent, the day is at hand: let us therefore cast off the works of darkness, and let us put on the armour of light. Let us walk honestly, as in the day; not in rioting and drunkenness, not in chambering and wantonness, not in strife and envying. But put ye on the Lord Jesus Christ, and make not provision for the flesh, to fulfil the lusts thereof. Romans 13:12-14

Son of man, I have made thee a watchman unto the house of Israel: therefore hear the word at my mouth, and give them warning from me. When I say unto the wicked, Thou shalt surely die; and thou givest him not warning, nor speakest to warn the wicked from his wicked way, to save his life; the same wicked man shall die in his iniquity; but his blood will I require at thine hand. Yet if thou warn the wicked, and he turn not from his wickedness, nor from his wicked way, he shall die in his iniquity; but thou hast delivered thy soul.
Again, When a righteous man doth turn from his righteousness, and commit iniquity, and I lay a stumblingblock before him, he shall die: because thou hast not given him warning, he shall die in his sin, and his righteousness which he hath done shall not be remembered; but his blood will I require at thine hand. Nevertheless if thou warn the righteous man, that the righteous sin not, and he doth not sin, he shall surely live, because he is warned; also thou hast delivered thy soul. Ezekiel 3:17-21