Edit: Red Squares And Equal Signshttp://www.theblaze.com/stories/2013/03/27/why-are-you-seeing-all-those-red-squares-as-facebook-profile-pictures/
You know, thinking about it now, the idea of using an equal sign to advertise support for homosexual marriage is rather unintentionally admitting that the idea of said "marriage" is fundamentally incorrect, especially if you happen to be a supporter that happens to be Christian.
"For this cause a man shall leave his father and mother; and shall cleave to his wife. 8And they two shall be in one flesh. Therefore now they are not two, but one flesh" - Matthew 19:7,8
These verses have a double meaning. The man and wife because one in almost everything except physically (that is to say, in flesh) unless they have a child, which would then contain the genetic information of the man and woman, thus making them both one flesh. An equal sign is basically the ultimate visual analogy to the old law of magnetism that opposites attract and similar poles repel. So too can to parallel