For a true separation of church and state, let's separate the religious and civil parts of the commitment of two people.
Have two separate ceremonies for a couple's civil and legal commitment, as is done in other countries. For civil and legal purposes, including Social Security, inheritance, health care decisions, property and parent rights, etc., use a civil process that grants some other term other than marriage, like "civil union," to describe the relationship under the law.
Keep the clergy entirely out of civil matters, and leave the term "marriage" to them. They could no longer say, "I now pronounce you man and wife under the laws of the state of Utah."
Ralph P. Schamel
Salt Lake City