In that day shalt thou not be ashamed for all thy doings - Because God, forgiving them, will blot them out and no more remember them. This was first fulfilled in the Gospel. Cyril: “No one can doubt that when Christ came in the flesh, there was an amnesty and remission to all who believed. ‘For we are justified not by works of righteousness which we have done, but according to His great mercy.’ But we have been released from shame. For ‘He’ hath restored us to freedom of access to God, Who for our sakes arose from the dead, and for us ascended to heaven in the presence of the Father. ‘For Christ, our Forerunner, hath ascended for us now to appear in the presence of God.’ So then He took away the guilt of all and freed believers from failures and shame.” Peter, even in heaven, must remember his denial of our Lord, yet not so as to be ashamed or pained anymore, since the exceeding love of God will remove all shame or pain.
Rup.: “Mighty promise, mighty consolation. Now, before that Day comes, the Day of My Resurrection, thou wilt be ashamed and not without reason, since thou ownest by a true confession, ‘all our righteousnesses are as filthy rags’ Isaiah 64:6. But at that Day it will not be so, especially when that shall be which I promise thee in the prophets and the Psalms, ‘There shall be a Fountain opened for sin and for uncleanness’ Zechariah 13:1; whence David also, exulting in good hope of the Holy Spirit, saith, ‘Thou shalt wash me and I shall be whiter than snow’ Psalms 51:7. For though he elsewhere saith, ‘they looked unto Him and were lightened, and their faces were not ashamed’ Psalms 34:5, yet in this mortal life, when the Day of My Resurrection doth not fully shine upon thee, thou art after some sort ashamed; as it is written, ‘What fruit had ye then in those things whereof ye are now ashamed?’ Romans 6:21, but that shame will bring glory, and, when that glory cometh in its place, will wholly pass away. But when the fullness of that day shall come, the fullness of My Resurrection, when the members shall rise, as the Head hath risen, will the memory of past foulness bring any confusion? Yea the very memory of the miseries will be the richest subject of singing, according to that, ‘My song shall be alway of the loving-kindness of the Lord’ Psalms 89:1.” For how shall the redeemed forget the mercies of their redemption, or yet how feel a painful shame even of the very miseries, out of which they were redeemed by the fullness of the overstreaming Love of God?
For then will I take away out of the midst of thee them that rejoice in thy pride - (Those of thee who exult in pride.) All confusion shall (cease, because all pride shall cease, the parent of sin and confusion. The very gift of God becomes to the carnal a source of pride. Pride was to the Jew also the great hindrance to the reception of the Gospel. He made his “boast of the law,” yea, in God Himself, that he “knew His will,” and was a “guide of others” Romans 2:17-20, Romans 2:23, and so was the more indignant, that the pagan was made equal to him, and that he too was called to repentance and faith in Christ. So, “going about to establish his own righteousness, he did not submit himself to the righteousness of God,” but shut himself out from the faith and grace and salvation of Christ, and rejected Himself. So (Rup.), “thy pride” may be the pride in being the people of God, and having Abraham for their father. “And thou shalt no more be haughty in My holy mountain,” “but thou shalt stand in the great and everlasting abiding-place of humility, knowing perfectly, that thou now ‘knowest in part’ only, and confessest truly that no one ever could or can by his own works be justified in the sight of God. ‘For all have sinned and come short of the glory of God’ Romans 3:23.” Pride which is ever offensive to God, is yet more hideous in a holy place or a holy office, “in” Mount Sion where the temple was or in the Christian priesthood.