In my opinion yes, gay marriage should be legalized and in every state. The decision to get married should not be limited based on the sex of the two individuals. It should be the decision of those who want to wed. If two people find themselves in a relationship that has developed to where they feel strong enough of a bond where marriage would be the next step, then they should have the opportunity to do so.
Every state should legally have to accept and offer all the opportunities to gay couples that are given to heterosexual couples. However whether or not a church wants to marry a gay couple should be up to the church and not the government. Some find this act immoral and against what they believe in, therefore the decision should be up to them.
A few topics that are frequently argued about when it comes to this question are abilities to raise children, divorce of the couples, and way of living. When it comes to raising children, gay people are just as physically and emotionally capable to raise children as a heterosexual person. People are going to get divorced regardless of their sexual orientation, it a risk that comes with getting married and is a known possible outcome that everyone getting married is aware of. The way of living that a married couple chooses should be a personal choice and no one has the right to try and tell or dictate how someone should live their life.
The main point I am trying to get across is that we should not try to control how certain people want to live and who they want to share their experiences with along the way. Everyone should have the right to choose what makes them happy the most and to pursue whatever it may be. We are all humans and because of that we are going to make mistakes. Those mistakes, however, are not made because one is gay but because they are simply human.