He is the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world.
NIV
And He [that same Jesus Himself] is the propitiation (the atoning sacrifice) for our sins, and not for ours alone but also for [the sins of] the whole world.
AMP
And he is the propitiation for our sins: and not for our's only, but also for the sins of the whole world.
KJV
God presented Christ as a sacrifice of atonement, through the shedding of his blood – to be received by faith. He did this to demonstrate his justice, because in his forbearance he had left the sins committed beforehand unpunished –
NIV
Whom God put forward [before the eyes of all] as a mercy seat and propitiation by His blood [the cleansing and life-giving sacrifice of atonement and reconciliation, to be received] through faith. This was to show God's righteousness, because in His divine forbearance He had passed over and ignored former sins without punishment.
AMP
Whom God hath set forth to be a propitiation through faith in his blood, to declare his righteousness for the remission of sins that are past, through the forbearance of God;
KJV
For this reason he had to be made like his brothers and sisters 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.
NIV
So it is evident that it was essential that He be made like His brethren in every respect, in order that He might become a merciful (sympathetic) and faithful High Priest in the things related to God, to make atonement and propitiation for the people's sins.
AMP
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.
KJV