3 For every high priest is appointed to offer both gifts and sacrifices. Therefore it is necessary that this One also have something to offer. 4 For if He were on earth, He would not be a priest, since there are priests who offer the gifts according to the law;
The argument of verses 3–5 is a comparison and contrast between the Levitical priestly ministry on earth to that of Christ’s heavenly ministry. The new ministry of Christ is set in opposition to the Levitical ministry.
“For” gives the reason Christ is the minister of the sanctuary (He 8:2).
every high priest is appointed to offer both gifts [meal offerings] and sacrifices [blood offerings].
The Old Testament high priest regularly offered gifts and sacrifices (He 5:1). A high priest must offer something.
Therefore it is necessary that this One [Jesus] also have something to offer.
Since it is true previous high priests offered gifts and sacrifices, it follows that the High Priest would do so as well. Jesus offered His blood sacrifice to the Father to establish the fact He paid for the sins of the world. Jesus stands forever as the one who offered sacrifice for sin.
For if He [Jesus] were on earth,
The temple in Jerusalem may have been still standing at the point of writing. Jesus was not on earth ministering in the temple but in heaven in His resurrected body. Christ’s heavenly priesthood was much superior to the earthly counterpart.
The “if” here is a hypothetical but false assumption (second class condition, contrary to the fact). The argument here assumes an untruth that Jesus was ministering on earth as a priest.
He would not be a priest,
Jesus could not offer sacrifices under the auspices of the Levitical priesthood because that would imply that ongoing sacrifices were still valid.
since there are priests who offer the gifts according to the law;
Christ could not have been a priest of the Mosaic Covenant or do their duties, one of which was to constantly offer sacrifice for sin. Christ could not make the presentation of His gift on earth since He is a priest forever.
Our Lord did not offer propitiation for our sin in heaven but on the cross.
The Lord does not offer sacrifices in heaven. Old Testament sacrifices were an ongoing affair, but Christ’s was a one-time event on earth (He 9:24–28). It was an offer of Himself on the cross (He 9:13, 14). He now serves as a High Priest in heaven to personally represent us there.