Because it is a kingdom of priests, the People of Israel are therefore a people that carries the message of God.
The entire people, including each person in it, is a representative and emissary of God in the world.
For this reason, when the Jew fails in his task or discredits himself in the eyes of others, he is not only slighting himself personally, but also defaming his role, and thus also defaming God’s name in the world.
When a Jew performs an immoral act—and the more he is identified with his Jewishness, the greater is the significance of his act—he engages in a serious transgression that the sages call a sacrilege.
–Rabbi Adin Steinsaltz