“Because I have seen the angel of Yahweh face to face.” Gideon remembered what God said to Moses, that no one could see Him and live (Exod. 33:20). But Gideon had been seeing this angel of God all along and had not died, so why would he die now? For one thing, this was not God Himself, but an angel. More to the point, however, was that even at the time of Moses people knew that God had appeared in human form to Adam and Eve (they heard His footsteps, Gen. 3:8), Abraham (Gen. 12:7; 15:1; 17:1; 18:1), Jacob (Gen. 28:13), and Moses and the elders of Israel (Exod. 24:9-11), and they had not died. What God told Moses was couched in that specific context and involved a human seeing God in a fuller way than God’s appearance in human form communicated.
There may be other thoughts going through Gideon’s mind as well as the idea that seeing God could be fatal. Gideon may think that God might be upset that Gideon did not recognize who he was speaking to earlier in the conversation, and also Gideon may have had in mind that there were times when angels came to destroy, such as at Sodom and Gomorrah, the angel of death in Egypt at the Passover, the angel that opposed Balaam the false prophet (Num. 22:23); the angel that could have destroyed Jerusalem (2 Sam. 24:16); the angel that destroyed the Assyrian army (Isa. 37:36); and the angel that killed Herod (Acts 12:23).
[For more on God appearing in human form, see commentary on Gen. 18:1 and Acts 7:55.]