From: Hebrews 4:14-16
Our Confidence is Based on Christ's Priesthood
 Since then we have a great high priest who has passed through the heavens, Jesus, the Son of God, let us hold fast our confession.  For we have not a high priest who is unable to sympathize with our weaknesses, but one who in every respect has been tempted as we are, yet without sinning.  Let us then with confidence draw near to the throne of grace, that we may receive mercy and find grace to help in time of need.
14-16. The text now reverts to its main theme (cf. 2:17), that is, the priesthood of Christ. It highlights the dignity of the new high priest, who has passed through the heavens; and His mercy, too, for He sympathizes with our weaknesses. We have, therefore, every reason to approach Him with confidence. "The believers were at that time in a storm of temptation; that is why the Apostle is consoling them, saying that our High Priest not only knows, as God, the weaknesses of our nature: as man, He has also experienced the sufferings that affect us, although He was free from sin. Since He knows our weaknesses so well, He can give us the help we need, and when He comes to judge us, He will take that weakness into account in His sentence" ("Interpretatio Ep. Ad Haebreos, ad loc.").
We should respond to the Lord's goodness by staying true to our profession of faith. The confession or profession of faith referred to here is not simply an external declaration: external confession is necessary but there must also be commitment and a spirit of fidelity. A Christian needs to live up to all the demands of his calling; he should be single-minded and free from doubts.
15. "If we should some time find ourselves sorely tempted by our enemies, it will greatly help us to remember that we have on our side a high priest who is most compassionate, for He chose to experience all kinds of temptation" ("St. Pius V Catechism", IV, 15, 14). In order to understand and help a sinner to get over his falls and cope with temptation, one does not oneself need to have experience of being tempted; in fact, only one who does not sin knows the full force of temptation, because the sinner gives in prior to resisting to the end. Christ never yielded to temptation. He therefore experienced much more than we do (because we are often defeated by temptation) the full rigor and violence of those temptations which He chose to undergo as man at particular points in His life. Our Lord, then, allowed Himself to be tempted, in order to set us an example and prevent us from ever losing confidence in our ability to resist temptation with the help of grace (cf. notes on Matthew 4:1-11 and paragraph).
"There is no man", St. Jerome comments, "who can resist all tests except He who, made in our likeness, has experienced everything but sin" ("Comm. In Ioannam", II, 46). Christ's inlessness, often affirmed in Sacred Scripture (Romans 8:3; 2 Corinthians 5:21; John 8:46; 1 Peter 1:19; 2:21-24), follows logically from His being God and from His human integrity and holiness. At the same time Christ's weakness, which He chose to experience out of love for us, is a kind of invitation from God to pray for strength to resist sin. "Let us adore Christ who emptied Himself to assume the condition of a slave. He was tempted in every way that we are, but did not sin. Let us turn in prayer to Him, saying, 'You took on our human weakness. Be the eyes of the blind, the strength of the weak, the friend of the lonely'" ("Liturgy of the Hours", Christmas Day, Evening Prayer I).
16. The "throne" is the symbol of Christ's authority; He is King of the living and the dead. But here it speaks of a "throne of grace": through the salvation worked by Christ, the compassionate Priest and Intercessor, God's throne has become a judgment seat from which mercy flows. Christ has initiated for mankind a time of forgiveness and sanctification in which He does not yet manifest His position as Sovereign Judge. Christ's priesthood did not cease to operate with His death; it continues in Heaven, where He forever pleads on our behalf, and therefore we should have confident recourse to Him.
"What security should be ours in considering the mercy of the Lord! 'He has but to cry for redress, and I, the Ever-Merciful, will listen to him' (Exodus 22:27). It is an invitation, a promise that He will not fail to fulfill. 'Let us then with confidence draw near to the throne of grace, and we may receive mercy and find grace to help in time of need'. The enemies of our sanctification will be rendered powerless if the mercy of God goes before us. And if through our own fault and human weakness we should fall, the Lord comes to our aid and raises us up" (St. J. Escriva, "Christ Is Passing By", 7).
Source: "The Navarre Bible: Text and Commentaries". Biblical text taken from the Revised Standard Version and New Vulgate. Commentaries made by members of the Faculty of Theology of the University of Navarre, Spain. Published by Four Courts Press, Kill Lane, Blackrock, Co. Dublin, Ireland. Reprinted with permission from Four Courts Press and Scepter Publishers, the U.S. publisher.