Of course.And many Christians (although I think this is changing for the better) violate the Golden Rule in relation to many other humans.
How often does it need explaining that calling yourself a Christian doesn't really make you one. It might be an aspiration but there also might be, or likely be, failings along the line.One of the most obvious examples is homosexuals. Many Christians treat homosexuals like crap, even some who are "nice" to them because of those Christian's beliefs. Most Christians would not want to be told that their beliefs will get them to a negative place, yet those same people do not see it as wrong for them to tell others this. Another example is the insistence that those who aren't Christian will go to hell or go somewhere negative in death. Sure, other religions do this too, but that doesn't mean it is consistent with the Golden Rule for any of them.
When the President takes the oath of office, he swears on the Bible to uphold the Constitution. He doesn't swear on the Constitution to uphold the Bible.
"Human kindness has never weakened the stamina or softened the fiber of a free people. A nation does not have to be cruel to be tough."
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"A woman is like a teabag, you never know how strong she is until she gets in hot water." - Eleanor Roosevelt
Keep your religion out of other people's marriages.