This is horrible advice because in common law marriage states, religious marriages are legal marriages.
All it takes is the wife filing for divorce and establishing that you put yourself out to the community as married and the courts will recognize the marriage.
Religious marriage is ironclad, documentary PROOF that you put yourself out as married so this is bad, bad advice.
These are the common law marriage states:
District of Columbia
Georgia (if created before 1/1/97)
Idaho (if created before 1/1/96)
New Hampshire (for inheritance purposes only)
Ohio (if created before 10/10/91)
Oklahoma (possibly only if created before 11/1/98. Oklahoma’s laws and court decisions may be in conflict about whether common law marriages formed in that state after 11/1/98 will be recognized.)
Pennsylvania (if created before 1/1/05)
Even if you do not live in one of these states, but you spent time in a state that does recognize common law marriage, “hold yourself out as married,” and then return or move to a state that doesn’t recognize it, you are still married (since states all recognize marriages that occurred in other states).