F B Meyer beautifully describes how and why the comforting truth of Hebrews 4:14-16 follows the convicting truth of Hebrews 4:12-13…


We deceive man, and sometimes ourselves; but not our great High-Priest. He sees all, that secret sin; that lurking enmity; that closed chamber; that hidden burglar; that masked assassin; that stowaway; that declension of heart; that little rift within the lute; that speck of decay in the luscious fruit. And thus it is that men are kept out of the Canaan of God’s rest, because he sees the evil heart of unbelief which departs from himself; and on account of which he swears now, as of old, “they shall not enter into my rest.”


Is it not a marvel that he who knows so much about us should love us still? It were indeed an inexplicable mystery, save for the truth of the words which so sweetly follow: “Seeing, then, that we have a great High-Priest.” He has a priest’s heart. His scrutiny is not one of morbid or idle curiosity, but of a surgeon, who intently examines the source of disease with pity and tenderness, and resolves to extirpate it as quickly and as painlessly as possible.


Is it not frequently the case that fuller knowledge will beget love, which once seemed impossible? There are some people whose faces are so hard, and their eyes so cold, that we are instantly repelled; but if we knew all, how they have been pierced and wounded, and disappointed, we should begin to pity them, and pity is close kinsman to love. The Saviour has known us from all eternity, our downsittings and uprisings, our secret possibilities of evil, our unfathomed depths of waywardness and depravity; and yet he loves us, and will love us. “He knows all, But loves us better than he knows.” And out of this love, which wells up perennially in the heart of Jesus, unfrozen by the winter of our neglect, Unstaunched by the demands of our fickleness, there comes the stern discipline of which this passage proceeds to speak.