ANSWER: The Hebrew epistle looks at Christians as journeying can through the wilderness to their heavenly home, and the writer seems to set' that some were in danger of going back to Judaism. Some had grown dull of hearing and had become such as had need of milk, not of strong food (Heb. 5:11-1211Of whom we have many things to say, and hard to be uttered, seeing ye are dull of hearing. 12For when for the time ye ought to be teachers, ye have need that one teach you again which be the first principles of the oracles of God; and are become such as have need of milk, and not of strong meat. (Hebrews 5:11‑12)). So they are exhorted to hold fast the confidence and the rejoicing of the hope firm into the end (ch. 3:6,14). Among other warnings we find some in this chapter: 10. Verse 25 continues an exhortation to hold fast the confession of the hope without wavering (for He is faithful who has promised), and to consider one another to provoke unto love and good works by doing them, and not to forsake the assembling of ourselves together. The "ourselves" are those who know redemption, those who are sanctified by Christ's one offering. It is by this means they are built up and strengthened in their faith, and, with Christ in the midst, see Him and have their hearts filled with joy.
The manner of some seemed to be to stay away, and, indeed, we need this exhortation, for some seem to look on the assembling of ourselves together as a matter of choice. They come when they please, and stay away as they please.
With the Hebrews this was dangerous ground; for all falling away in this epistle is really apostasy from Christ. Self-will in any of us is sad indeed, so we need to exhort one another, especially as we think of the day soon coming when all our ways will be manifested whether we are doing OUT own will or the will of God.