The high priest of Israel wore a gold headband on his forehead that read "HOLY TO THE LORD." The reason for the headband--the "so that" that Bible readers should always pay attention to--was "so that the offerings will be acceptable before God."
In the New Testament, God has designated all Christians as priests, and in Revelation, we learn that we will have something tattooed on our foreheads: His name.
Hmm, somehow I missed that bit about the tattoo when I read those life-affirming, hope-sustaining words about no more death nor crying nor pain, about the presence of the Lamb and no need for the sun to shine.
We have been anointed, ordained, consecrated (we read about that in Exodus 28 as read) to the service of God. He puts His name on us with permanent ink; we'll never lose that job.
But like Aaron and all His descendants, we cannot make an offering that is acceptable to God without that mark.
Shades of Cain and Abel's sacrifices. One was acceptable, the other wasn't.
Our offerings--the living sacrifice of our lives--is only acceptable to God in the extent to which we bear His name, His character, in our lives.