Its called "expiation", a means of atonement.
"Therefore he had to be made like his brethren in every respect, so that he might become a merciful and faithful high priest in the service of God, to make expiation for the sins of the people." - Hebrews 2:17
That’s not nearly the same thing. Jesus made atonement for our sins. That is not penance.
Jesus paid the penalty so that we don’t have to. The penalty for our sin is death, a penalty which none of us is capable of paying, no matter what prayers and deeds some priest assigns to us. Forgiveness is offered freely so that we don’t have to pay what we can’t.
Jesus didn’t die to set an example of how we are to consider or treat our sin. He died so that we don’t have to. God gets no glory if we can save ourselves. It’s a gift so that no one can boast.
http://www.merriam-webster.com/dictionary/penance
1 : an act of self-abasement, mortification, or devotion performed to show sorrow or repentance for sin
2 : a sacramental rite that is practiced in Roman, Eastern, and some Anglican churches and that consists of private confession, absolution, and a penance directed by the confessor
3 : something (as a hardship or penalty) resembling an act of penance (as in compensating for an offense)
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http://www.merriam-webster.com/dictionary/expiation
1 : the act of making atonement
2: the means by which atonement is made
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You need to get a better translation of the Bible.
http://bible.cc/hebrews/2-17.htm
New International Version (©1984)
For this reason he had to be made like his brothers in every way, in order that he might become a merciful and faithful high priest in service to God, and that he might make atonement for the sins of the people.
New Living Translation (©2007)
Therefore, it was necessary for him to be made in every respect like us, his brothers and sisters, so that he could be our merciful and faithful High Priest before God. Then he could offer a sacrifice that would take away the sins of the people.
English Standard Version (©2001)
Therefore he had to be made like his brothers in every respect, so that he might become a merciful and faithful high priest in the service of God, to make propitiation for the sins of the people.
New American Standard Bible (©1995)
Therefore, He had to be made like His brethren in all things, so that He might become a merciful and faithful high priest in things pertaining to God, to make propitiation for the sins of the people.
International Standard Version (©2008)
thereby becoming like his brothers in every way, so that he could be a merciful and faithful high priest in service to God and could atone for the people’s sins.
GOD’S WORD® Translation (©1995)
Therefore, he had to become like his brothers and sisters so that he could be merciful. He became like them so that he could serve as a faithful chief priest in God’s presence and make peace with God for their sins.
King James Bible
Wherefore in all things it behoved him to be made like unto his brethren, that he might be a merciful and faithful high priest in things pertaining to God, to make reconciliation for the sins of the people.
American King James Version
Why in all things it behooved him to be made like to his brothers, that he might be a merciful and faithful high priest in things pertaining to God, to make reconciliation for the sins of the people.
American Standard Version
Wherefore it behooved him in all things to be made like unto his brethren, that he might become a merciful and faithful high priest in things pertaining to God, to make propitiation for the sins of the people.
Bible in Basic English
Because of this it was necessary for him to be made like his brothers in every way, so that he might be a high priest full of mercy and keeping faith in everything to do with God, making offerings for the sins of the people.
Douay-Rheims Bible
Wherefore it behoved him in all things to be made like unto his brethren, that he might become a merciful and faithful priest before God, that he might be a propitiation for the sins of the people.
Darby Bible Translation
Wherefore it behoved him in all things to be made like to his brethren, that he might be a merciful and faithful high priest in things relating to God, to make propitiation for the sins of the people;
English Revised Version
Wherefore it behoved him in all things to be made like unto his brethren, that he might be a merciful and faithful high priest in things pertaining to God, to make propitiation for the sins of the people.
Webster’s Bible Translation
Wherefore in all things it behooved him to be made like his brethren; that he might be a merciful and faithful High Priest in things pertaining to God, to make reconciliation for the sins of the people.
Weymouth New Testament
And for this purpose it was necessary that in all respects He should be made to resemble His brothers, so that He might become a compassionate and faithful High Priest in things relating to God, in order to atone for the sins of the people.
World English Bible
Therefore he was obligated in all things to be made like his brothers, that he might become a merciful and faithful high priest in things pertaining to God, to make atonement for the sins of the people.
Young’s Literal Translation
wherefore it did behove him in all things to be made like to the brethren, that he might become a kind and stedfast chief-priest in the things with God, to make propitiation for the sins of the people,
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http://strongsnumbers.com/greek/2433.htm
hilaskomai - to be propitious, make propitiation for