continuing from Wednesday...
... So what can we say about the situation behind Hebrews without speculating too much? There are enough hints here and there for us to come up with a basic picture. Hebrews 10:35-36 is a good place to start: "Therefore, do not throw away your confidence, which has a great reward. For you have need of endurance, so that when you have done the will of God, you may receive what was promised" (NASB).
It's not a stretch to think that the audience of Hebrews is having some doubts about its faith. The author pushes them boldly: "We do not belong to those who shrink back and are destroyed, but to those who have faith and are saved" (10:39). Although we often read the "Hall of Faith" of Hebrews 11 all by itself, it flows directly from this encouragement to keep going. The heroes of Hebrews 11 are examples of individuals who kept going and were faithful despite hardships and persecution. So Hebrews 12, after all those examples are done, concludes that the audience needs to keep running the race with patience, mindful of all the examples in the stands who are cheering them on (12:1-2).
The earlier warnings of Hebrews fit well into this context. The audience needs to "pay the most careful attention" to their faith. Those who strayed from the covenant under Moses were severely punished. Can you imagine, the author then asks, "How shall we escape if we neglect so great a salvation?" (2:2), which is offered under someone much more authoritative than Moses. We will look at the other passages like these later in the chapter.
What is striking about these warnings not to "drift away" (2:1) is that this community of faith has actually believed for some time. Hebrews 10:32 urges them to remember the way they endured in earlier times of persecution. In that earlier time they were publicly disgraced and suffered along with others who were imprisoned, even losing property. Hebrews 6:10 recalls how the community had been faithful in the past. Another intriguing allusion is to the previous outcome of their leaders' lives in 13:7. Had they been martyred?
These comments fit into more than one location in the early church, even given what little we know. It's most common to try to connect them to one or more persecution of the church in Rome. For example, in AD49, some Christian Jews were expelled from Rome because of controversies in the synagogues over whether Jesus was the Messiah. Then in AD64, Nero put many Christian leaders to death in Rome, blaming them for the fire of Rome.
So one of the key factors behind the sermon of Hebrews is a sense of impending persecution. They have not yet faced martyrdom this time around (12:4). Somehow connected to this fear is also an inadequate confidence in the atonement provided by Jesus' death. This is the most ambiguous aspect of Hebrews' situation to us, because the author isn't really clear about what is specifically troubling them.
Hebrews 13:9 does mention some strange teaching in their context involving foods that connect somehow to the Old Testament sacrificial system. On the one hand, it's hard to imagine anyone calling temple sacrifices "strange teaching," since it comes straight out of the Old Testament. Perhaps there was some synagogue meal somewhere that some Jews were teaching substituted for temple sacrifices somehow?
However, this curious comment at the end of Hebrews seems more of an aside than the central issue. The central part of Hebrews effectively argues that Jesus' death completely replaces the entire sacrificial system of the Old Testament. Either the author is trying to discourage this community from using the Jerusalem temple or, as I think more likely, he is trying to bolster their confidence in the days after the temple and Jerusalem has been destroyed.
So he reminds them that "here we do not have an enduring city" (13:14). Rather, they are like Abraham, who was a stranger in the land (11:9) and was looking for a new country (11:14) and a new city (11:10). Meanwhile, the earthly sacrificial system was "growing old" and "ready to disappear" (8:13, NASB).
So Hebrews was a sermon written to a troubled community in danger of turning away from the living God (3:12).  They fear that they are about to face hard times from secular, very likely Roman authorities. Not only are they dreading this prospect, since they have faced such persecution before, but they are somehow doubting the full sufficiency of Christ's death to cover their sins. In some way, the author sees his argument about Christ's atonement bolstering their confidence in the faith enough for them to keep going until Christ finally returns...
 Mention of turning away from the "living" God fits a primarily Gentile audience much better than a Jewish one, since a Jew would not be turning away from Yahweh to the "dead gods" of the Gentiles. Similarly, the list of beginning teachings in Hebrews 6:1-2 does not read like the kinds of teaching a Jew would have needed to learn when believing on Christ for the first time but the kinds of first teachings a Gentile would have learned.
We can imagine that the destruction of Jerusalem and its temple might have created a serious faith crisis for some Gentile converts to Christian Judaism. By contrast, it is otherwise hard to connect the audience's sense of impending persecution with it being troubled over atonement. In what pre-70AD setting would bolstering the audience's confidence in Christ's atonement help them face impending persecution? Meanwhile, we can imagine some strange synagogue teachings arising in relation to atonement after the temple was destroyed.