There are three things about this reference to "sins of the holy things" but before getting to those we must recall that "holy things" are simply things dedicated to a special function; in this case, it was the "holy gifts" - objects and money donated to support the Levitical and high priesthood.
- The guilt of the holy things refers in the first instance to the fact that any gift was made by human and thus less than perfect. However, in its state of imperfection, it was still accepted by God and consecrated (= made holy, dedicated, set apart, etc) to sacred service. The Cambridge commentary makes the same point:
bear the iniquity, &c.] i.e. take upon himself the guilt of any ritual
error or mistake made accidentally in offering the holy things; cf.
Leviticus 22:16. Elsewhere the expression becomes equivalent to be
responsible for (Numbers 18:1; Numbers 18:23). Cf. LOT. p. 50, No.
- The givers of these gifts gave them with impure motives because they were sinful humans possessed of sinful, imperfect human natures. Despite this, the gifts were accepted for sacred service. Ellicott makes the same point:
(38) That Aaron may bear the iniquity of the holy things.—The “holy
things” are the offerings brought by the people. These would always
have some “iniquity” attaching to them, some imperfection, owing to
the imperfection of human nature and the mixed character of human
motives. The high priest’s official holiness enabled him to present to
God offerings thus imperfect without offending Him. It was accepted as
purging the offerings from their impurity.
- The High Priest represented the coming Messiah who accepted those who come to Him as they are with all their frailties and imperfections. The Messiah accepts us when we come to him but we do not stay as we are by "grow into Christ" (Eph 4:15, 16), "purifying ourselves" (2 Cor 7:1), "not conforming to the pattern of this world" (Rom 12:1, 2), etc. Benson arrives at a similar position:
Herein he was a type of Christ, the great Mediator between God and
man. Through him, what is amiss in our services, is pardoned: even
this would be our ruin, if God should enter into judgment with us: but
Christ, our High-Priest, bears this iniquity; bears it for us, so as
to bear it from us. Through him, likewise, what is good is accepted;
our persons, our performances, are pleasing to God upon the account of
Christ’s intercession, and not otherwise. His being holiness to the
Lord, recommends all those to the divine favour that believe in him.
Having such a High-Priest, we come boldly to the throne of grace.