3 who being the brightness of His glory and the express image of His person, and upholding all things by the word of His power, when He had by Himself purged our sins, sat down at the right hand of the Majesty on high,
3 who [the Son] being the brightness [radiance, effulgence] of His [God’s] glory
The third declaration about the superiority of the Son is that He is the revealer of the Father. The word “brightness” is the radiance that bursts out of brilliant light. He is like the glorious dawn at sunrise. The eternally new rays of light pierce the darkness and cast vision to everything around it (Jn 1:14).
“Being” is the Son’s pre-existent and essential being as God. The Son radiates the glory of God in His absolute and timeless existence.
The word “brightness” means outshining. God’s “glory” reflects the Son’s nature, character, attributes, and acts. The glory of God is the manifestation of His being. The Lord is the effulgence of God’s glory because He is of the same nature as the Father. The Son, above all, manifests God as no other. We know about God through the revelation of His Son. He is the brightness we see about God.
The Son is the manifestation of God’s glorious presence.
The Son is not just like the Father; His person is not the same. However, He shares the same essence as the Father. He is the out-raying of divine glory. He exhibited in Himself the glory of God’s being. He is the personification of God’s glory. The Son is superior to anything or anyone else because He is the effulgence of God’s glory. He radiates God’s glory, attributes, majesty, and work. This is something that happens because of His intrinsic deity.
The statement is not that the Son became the brightness of His glory, but rather that He existed eternally in that glory. There is a oneness between the Father and Son. The Son’s inherent glory was the glory of His Father. The Son gets His glory from deity (Jn 1:14). His radiance is an extension of the glory of God. The deity of Christ was a big issue to the Jews of the first century, as it is today.