Contrary to the rewrites of scripture/history which are regularly propagated here by many, the epistle to the Hebrews has to do with turning away from ALL TYPES OF SIN. For example, we read:
Hebrews chapter 3
[1] Wherefore, holy brethren, partakers of the heavenly calling, consider the Apostle and High Priest of our profession, Christ Jesus;
[2] Who was faithful to him that appointed him, as also Moses was faithful in all his house.
[3] For this man was counted worthy of more glory than Moses, inasmuch as he who hath builded the house hath more honour than the house.
[4] For every house is builded by some man; but he that built all things is God.
[5] And Moses verily was faithful in all his house, as a servant, for a testimony of those things which were to be spoken after;
[6] But Christ as a son over his own house; whose house are we, if we hold fast the confidence and the rejoicing of the hope firm unto the end.
[7] Wherefore (as the Holy Ghost saith, To day if ye will hear his voice,
[8] Harden not your hearts, as in the provocation, in the day of temptation in the wilderness:
[9] When your fathers tempted me, proved me, and saw my works forty years.
[10] Wherefore I was grieved with that generation, and said, They do alway err in their heart; and they have not known my ways.
[11] So I sware in my wrath, They shall not enter into my rest.)
[12] 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.
[14] For we are made partakers of Christ, if we hold the beginning of our confidence stedfast unto the end;
[15] While it is said, To day if ye will hear his voice, harden not your hearts, as in the provocation.
[16] For some, when they had heard, did provoke: howbeit not all that came out of Egypt by Moses.
[17] But with whom was he grieved forty years? was it not with them that had sinned, whose carcases fell in the wilderness?
[18] And to whom sware he that they should not enter into his rest, but to them that believed not?
[19] So we see that they could not enter in because of unbelief.
What types of sins caused the majority of the children of Israel to be overthrown in the wilderness IN GOD'S WRATH?
Was it simply a matter of "their self imposed, self centered religion of works and trying to earn their way to heaven" as you allege?
Not even close...so spare me/us the rewrites of scripture/history, okay?
Paul gives us a pretty good overview of their sins here:
I Corinthians chapter 10
[1] Moreover, brethren, I would not that ye should be ignorant, how that all our fathers were under the cloud, and all passed through the sea;
[2] And were all baptized unto Moses in the cloud and in the sea;
[3] And did all eat the same spiritual meat;
[4] And did all drink the same spiritual drink: for they drank of that spiritual Rock that followed them: and that Rock was Christ.
[5] But with many of them God was not well pleased: for they were overthrown in the wilderness.
[6] Now these things were our examples, to the intent we should not lust after evil things, as they also lusted.
[7] Neither be ye idolaters, as were some of them; as it is written, The people sat down to eat and drink, and rose up to play.
[8] Neither let us commit fornication, as some of them committed, and fell in one day three and twenty thousand.
[9] Neither let us tempt Christ, as some of them also tempted, and were destroyed of serpents.
[10] Neither murmur ye, as some of them also murmured, and were destroyed of the destroyer.
[11] Now all these things happened unto them for ensamples: and they are written for our admonition, upon whom the ends of the world are come.
[12] Wherefore let him that thinketh he standeth take heed lest he fall.
The children of Israel's sins included such things as "lusting after evil things", "idolatry", "fornication", "tempting Christ" and "murmuring" so, again, let's not rewrite scripture/history, okay? Why do you suppose that Paul warned his CHRISTIAN readers who "thought they stood" to "TAKE HEED LEST THEY FALL"? Don't tell me...let me guess...because Paul allegedly believed in "once saved, always saved", right? Don't kid yourself, friend. Also, don't even bother attempting to convince me or anybody else here for that matter that the type of "fall" which Paul was here describing was anything other than THE SAME EXACT TYPE OF FALLING THAT HE HAD JUST FINISHED DESCRIBING IN RELATION TO THE ISRAELITES OF OLD. Their "fall" will ultimately result in ETERNAL DAMNATION...even as GOD HAS SWORN that these same will not enter in His rest.