You shall not make wrongful use of the name of the Lord your God, for the Lord will not acquit anyone who misuses his name. - So I can't say "Goddamnit!" when I stub my toe? Breach of free speech.
You shall not covet your neighbour’s house. - Wait a minute. Now he's telling us what we can and can't think? Look, I appreciate the sentiment but I quite enjoy coveting things. If my neighbour (or anyone for that matter) has a nice house, I want to be able to think "Wow, I wish I lived in a house like that! That guy's a jerk, he doesn't deserve that house." As long as I then don't go and kill that guy, steal his house (and wife and ox, for that matter) that's OK in my book.
I won't deny that religion is, on the whole, responsible for the society that we have today. However, for every good thing religion (to use a blanket statement there) has done in the past (and there have been many) I could point to an instance where religion has done things to the detriment of progress, or I could point to an instance of religious persecution. I'm not saying that this negates the good things that it has brought about, I'm just saying that this argument isn't the best.
I can't really think of any modern Christian theocracies that use Biblical law to the detriment of the people, but I can't actually think of any modern Christian theocracies at all. I'm sure that if a Christian theocracy was formed in an unstable region the result would be quite similar to those Islamic theocracies
What if I say that the word 'BLUE' no longer refers to the colour blue, it refers to the colour orange. I have not added a meaning, I have completely changed the meaning. You say that the word 'marriage' cannot have two meanings. Well, we can quite easily change the word 'marriage' from meaning a union between an adult man and an adult woman to a union between two adult people, regardless of gender. It no longer means nothing, instead, the meaning has changed.
This has happened before and it will happen in the future. The meaning of words (especially words such as 'marriage' and 'equality' that have a direct effect on society) needs to change as our society, in turn, changes.
Consider the world of the past, where the word 'equality' only applied to white, male land-owners. This meaning completely contradicts modern usage of the word, as its meaning is far more universal.
