The food Gideon offered his visitor was what a person would normally set before a guest one wished to honor in a special way in that culture. The Angel directed Gideon to place the food on the rock as though it was a sacrifice on an altar.
The Angel's miracle convinced Gideon that He was God and that He would fulfill His promises to be with Gideon and to grant him victory. Perhaps Gideon remembered how God had consumed the sacrifice on the brazen altar similarly when the Israelites dedicated the tabernacle in the wilderness. If so, this memory might have encouraged him to believe that the same God who had delivered Israel then was still with His people and could deliver them again.
"The acceptance of the sacrifice was also a token of the acceptance of his person; it went to confirm the commission now given him, and to afford him every needed assurance of success."143
This miracle strengthened Gideon's faith greatly. In building an altar to Yahweh Gideon acknowledged Him as his God.
"God had taught Gideon that it was not his inadequacy but God's adequacy that really counted."144
God presented Himself to Gideon as the same God who had appeared to the patriarchs and had fulfilled His promises to them (cf. Gen. 18).
