Also, Warren W. Wiersbe has an amazing commentary on this point, too.
Warren essentially says that Stephen's speech opens with the glory of God and closes with the glory of God (Acts 7:55). He adds that that the entire time when Stephen had spoken, his face radiated the glory of God? Why? Because Israel was the only nation priviledged to have the glory of God as a part of it's inheritance (Romans 9:4). Therefore, the glory of God departed, first from the tabernacle (1 Samuel 4:19-22) and then from the temple (Ezekiel 10:4, 18). For God's glory was manifested when the Word was made flesh (John 1:14), but the nation of Israel had rejected Him, though.
Source:
http://www.amazon.com/Wiersbe-Bible-Commentary-Vol-Commentaries/dp/0781445418/
Warren essentially says that Stephen's speech opens with the glory of God and closes with the glory of God (Acts 7:55). He adds that that the entire time when Stephen had spoken, his face radiated the glory of God? Why? Because Israel was the only nation priviledged to have the glory of God as a part of it's inheritance (Romans 9:4). Therefore, the glory of God departed, first from the tabernacle (1 Samuel 4:19-22) and then from the temple (Ezekiel 10:4, 18). For God's glory was manifested when the Word was made flesh (John 1:14), but the nation of Israel had rejected Him, though.
Source:
http://www.amazon.com/Wiersbe-Bible-Commentary-Vol-Commentaries/dp/0781445418/