Read Matthew 23:8-10. These include that it is Wrong for anyone with GOD to have any titles. Only their names are to be used! So only call them by their own names.
Even Jesus was only called Jesus! No titles did he use. Yet Jesus was a higher ranking Jewish Rabbi!
As Mr & Mrs.
* Informally means casual so you would address a husband and wife by their first names. Formally is when you would use Mr. Doe or Mrs. Doe.
Mr & Mrs James Angstrom Jr.
Major and Mrs . . .
Dr. Mary Smith and Mr. James Doe
Just address the card to Mr and Mrs (husband's name). It's perfectly okay to address the husband and wife but to avoid offending the wife just do the Mr and Ms last name and you're probably safe.
Pastors George and Martha Maloney
How about Mr. and Mrs.
Governor and Mrs./Mr. Smith
* Major & Mrs. John Doe
Doctor Smith and his wife Reverend Smith (assuming she is using his last name).
Pastors George and Martha Maloney