Therefore, since we are surrounded by so great a cloud of witnesses, let us also lay aside every weight, and sin which clings so closely, and let us run with endurance the race that is set before us, looking to Jesus, the founder and perfecter of our faith, who for the joy that was set before him endured the cross, despising the shame, and is seated at the right hand of the throne of God. Consider him who endured from sinners such hostility against himself, so that you may not grow weary or fainthearted. (Heb. 12:1-3)Background
These Jewish Christians were struggling, on the verge of reverting back to Judaism. Perhaps triggered by persecution (Heb. 10:32-35). One possible scenario is the plight of Jewish Christians who returned to Rome after the edict of Claudius, only to have the persecution of Nero break out. The easier path would be to renounce Christ for the safety of Judaism, which was legally recognized.
For this reason the author emphasizes the superiority of Christ to the angels (Heb. 1-2), Moses and Joshua (Heb. 3-4), and Aaron (Heb. 5-10).
In 12:1-3 the writer encourages the people not to give up, but to run with endurance. Here are three points he makes in that admonition. We can run with endurance...
1) Because many people are cheering for us. "Since we are surrounded by so great a cloud of witnesses" (12:1). Referring to the pantheon of heroes and heroines in the faith listed in Heb. 11. We also have encouragement in each other (Heb. 3:13; 10:24-25).
2) As long as we get rid of unconfessed sin. "Let us lay aside every weight, and sin which clings so closely" (12:1). The sin in context us unbelief (3:12). But any unresolved sin weighs us down and destroys our race as Christians (see Psalm 32).
3) If we keep looking to Jesus. "Looking to Jesus" (12:2). Jesus ran the race before us, and His example shows us that while all of God's sons will suffer (Heb. 5:8-9; 12:4-7), that suffering is temporary. We have a reward like Jesus, who looked at the "joy that was set before him," exaltation at God's right hand. So, "consider him!" (12:3).