What does Hebrews 13:21 mean?

This verse continues a benediction beginning in verse 20. Immediately before that, the writer had asked for prayer from the readers (Hebrews 13:18). Verse 20 mentioned several of the big ideas explained in the letter so far. Among these are the idea of God offering believers peace (Hebrews 12:22–29), Christ as an example to be followed (Hebrews 12:2), resurrection (Hebrews 6:2; 11:19), and the eternal nature of the new covenant (Hebrews 10:12–14).

Here, the writer continues to recycle the major themes of his message. The reference to being equipped meshes with earlier comments about maintaining obedience to God (Hebrews 3:12). The trusting faith defined earlier in Hebrews means following God in obedience, even when we don't fully understand (Hebrews 12:1). Sometimes, as in the case of men like Abraham (Genesis 17:17), Moses (Exodus 4:1, 10), or Gideon (Judges 6:15), we may doubt that we're capable of achieving what God is asking. Faith, however, means relying on God to provide whatever we need in order to accomplish His will. This comment is extremely similar to Peter's statement in 1 Peter 5:10.

The idea that God "works in us" is key to understanding our life experiences. As stated earlier, some events in life are unhappy, but that doesn't mean they have no purpose. For the Christian believer, God's discipline and "training" are part of growing into a stronger, more capable believer (Hebrews 12:5–11). This also echoes Scriptures such as Philippians 2:13, which speaks of God working in us according to His will.