Defining marriage as one man and one woman is NOT discrimination. To say it is, is to show that you do not know or understand the meaning of discrimination. Right now, two individuals cannot enter into marriage without abiding by a few rules, which may vary depending on your specific state. For example, you must prove or attest that you are not related and that you do not have certain sexually transmitted diseases.
Marriage is much more than just a state issued liscense. The "intent" of this lisence is that it is not to expire. You do not need to re-certify or renew your marriage liscense. There are no ways that the state can come in and revoke or cancel your marriage. Every other state issued liscense you purchase has specific expiry limits and also conditions on which the state may revoke or cancel the liscense. I could explain other differences, but argument on the basis of a marriage just being a simple state issued liscense is an extremely weak on and shows you do not truly understand or appreciate the true meaning of marriage.
Marriage should not be issued simply on the basis of your sexual preference or who you love. I love my mom. Should I be allowed to marry her? I love my dog. Should I be allowed to marry her? Should I be allowed to marry two or more women?
The issue is also not specific to a religion. I only know of one religion that approves of a marriage between 2 members of the same sex. Which religion is that? Atheism. All other religions, that I am aware, share a unity in the morality of marriage being between man and woman (some allow poligamy) and most share a belief that same gender sex is undesirable. There is nothing PROGRESSIVE about having a belief that same gender relationships are acceptable, much less wanting to redefining concepts of marriage and the true meaning of a family. Beliefs such as this simply show that you stand against the grain of all major world religions, many of which have a several thousand year track record of holding these beliefs.
The voting record of 19 states has shown a majority interest in defining marriage as one man and one woman. Some states are in the 70%.