What does Hebrews 11:29 mean?

The key point in this passage of Hebrews is the necessity of faith. In particular, godly faith is not merely "belief," nor is it merely "obedience." Rather, biblical faith is a trust in God, based on what we know of Him, and in spite of what we do not know of the future (Hebrews 11:1–3). Most of the emphasis in prior verses has been on the fact that godly people demonstrate this kind of trust by their actions. Abraham obeyed God's seemingly impossible command regarding Isaac (Hebrews 11:17–19). Moses' parents defied a king, instead trusting God with the life of their child (Hebrews 11:23). Moses rejected his adoptive Egyptian family and identified with his persecuted Hebrew people instead (Hebrews 11:24–26). He also challenged the Pharaoh in order to rescue Israel from slavery and obeyed God's Passover commands to save them from the plague on the firstborn (Hebrews 11:27–28).

Here, the example given highlights a point made in verse 6. Namely, that those who do not have this kind of trusting, godly faith cannot please God. In particular, this means that obedience, without faith, is useless. The people of Israel were able to cross the Red Sea thanks to a miraculous parting of the waters by God (Exodus 14:21–22). When the Egyptian army, sent by a vengeful Pharaoh, attempted to follow them, they were obliterated by those same waves (Exodus 14:23–29).

In the context of this part of Hebrews, this example serves two purposes. First, it underscores the fact that robotically acting in a mimicry of faith, without an attitude of faith, is not going to result in God's favor. The Israelites crossed the Red Sea because they trusted God. The Egyptian army tried to cross the Red Sea because they saw Israel doing it, and wanted to follow them for revenge, but failed.

Secondly, this is an example of how obedience to God, driven by trusting faith, results in victory. The next example given is of another unlikely triumph of Israel, during their later conquest of the land of Canaan.