Firstly, gay (and lesbian) people have the right to get married because, quite frankly, they're humans too. If "straight" people are allowed to get married, so can gay people. If I put it out there plainly, marriage is not a religious ritual. Some might argue that marriage is an "institution ordained by God between a man and a woman" but there are plenty of atheists who get married. Neither is marriage a system to get children. Marriage is a legal contract. By denying gay people to get married, we are excluding them from our society. Yes, it is just a certificate, a little slip of paper that you could easily lose but to some gay people, it means the world to them so why not just let them get the marriage certificate they've wanted for so long? This would be a big step to gay people finally being able to fit into our society. Some politicians get all worked up and excited when it comes to racism and colour discrimination but if not allowing gay people to get married isn't discrimination, I don't know what is.
Currently, in 'marital' life a person can have 3 statuses. Married, single, or in a civil partnership (which before the laws were passed was legal for the LGBTQ community). The word 'marriage' started with only religious origins, and has begun to be recognised by the state- but it's not a matter of one size fits all. You need to have a religious marriage, and a civil marriage. I therefore suggest that we abolish the term marriage as a civil concept, and only have civil partnerships, to which all the benefits of marriage would accrue.
If the word marriage ceases to have any meaning, there will be no gay marriage which satisfies the resolution.
For the purposes of religion, let us assume that roughly 5% of the religious community says no to gay marriage. If, as Pro says YES, gay marriage all the time then that is infringing upon the rights of that community.
Your proposal of having a religious marriage and a civil marriage is extremely well thought-through and reasonable; however, you are not the commander of the universe, as in you are mostly powerless to do anything do change the marriage laws. This particular debate is about the existing marriage laws for gay peope and therefore although your point would be great in another situation, it is invalid here. Also, yes, a small perentage of the religious community says no to gay marriage. Regardless of how much that particular religious community is against gay marriage, it is wrong of them to impose their opinion on others. I, by no means am telling people that we should just ignore the group of people against gay marriage's opinion but other people shouldn't have to conform to their personal religious beliefs. History has proven time and time again that most traditional beliefs are wrong like children being seen and not heard and the people of the same gender being not allowed to get married is another one of them.