What "throne of grace" is he speaking of? that royal throne concerning which it is said, "The Lord said unto my Lord, Sit on My right hand." ( Ps. cx. 1 .)
What is "let us come boldly"? Because "we have a sinless High Priest" contending with the world. For, says He, "Be of good cheer, I have overcome the world" ( John xvi. 33 ); for, this is to suffer all things, and yet to be pure from sins. Although we (he means) are under sin, yet He is sinless.
How is it that we should "approach boldly"? Because now it is a throne of Grace, not a throne of Judgment. Therefore boldly, "that we may obtain mercy," even such as we are seeking.
--St. John Chrysostom, Homily 7 on Hebrews