How Does Congress Have Chaplains Without Violating the Separation of Church and State?

It is noteworthy that congressional chaplains do not demographically represent the American public, and quite strikingly so. Every congressional chaplain since 1789 has been a Christian man, and of those nearly all have been Protestant. Only one, the current Senate chaplain, Rev. Barry Black, has been a person of color. The only time that Muslim and Hindu chaplains have delivered prayers was as one-time guest clergy. It’s the same for women.