I want to start with stating there is nothing in the Constitution that dictates a "separation of church and state." The Constitution specifically dictates there will be no law "respecting the establishment of religion". In other words, no official state religion. As for "freedom from religion", this has been established in Supreme Court case history as a legitimate interpretation of that same statement.
I, too, have a Christian background. The reality is that the 10 commandments have little to do with our legal system. Contrary to the statements by the judge involved (and picked up by the press), our legal system is founded on English law, which was founded on Roman law, not Hebrew (or Christian) law. Of the 10 commandments, only three actually apply to our legal system, and these a have historical basis in many cultures (do not steal, do not murder, do not bear false witness.) The others do not apply to our legal system (No other gods before me, any graven image, take the name of god in vain, remember the sabbath day, honor thy father and mother, no adultry.) While there is some history with four and seven (sabbath day and adultry), even these have very little current application, particularly since the Jewish sabbith is Saturday, not Sunday.
This issue here has quite a bit to do with the public funding of the monument and the display in a manner which clearly suggested an official support of the content. If the judge wanted to display a plaque he paid for himself at his seat in the courtroom it would have been legal and acceptable.