Living In Sin

My church seems to believe that living together outside of marriage is a sin.  Well, read the April 26 Business section of the NewYork Times.  It has an article about all the financial reasons that older widows and widowers do not choose marriage but do live together.  Apparently, marriage for these people can have rather unfortunate financial ramifications.  This is an example where a church continues with the same teaching, though the real world has changed.  In the USA there are unintended consequences to "doing the right thing."  Would it not be better to help these people by talking about weighing various issues, including inheritance and taxes, before deciding what to do about becoming a "couple?"  Of course, maybe all these elderly people are living as brother and sister.  You think?