A. Equal in the same sense that interracial marriage bans made it so nobody could marry someone of a different race. That is equal as well as it applies across the board. However, it did not serve a legitimate or rational state interest and therefore was found unconstitutional. In the same way, same sex marriage bans discriminate on the basis of sex. No person can marry someone of the same sex, and that is equal, but it is not rational nor does it serve a legitimate state purpose.
B. As a general rule, children of same sex couples deserve the same rights and protections inherent in having married parents as do children of opposite sex couples. When you brought children into the argument you lost because opposite sex couples do not have a monopoly on raising children. People will and do procreate regardless of marriage and as such it is not a basis for discriminating who does and does not deserve to marry. To the contrary, the true basis for marriage in a modern society is on providing stable homes to raise children, of which over 30 years of evidence supports that same sex couples are well equipped to do.
C. In other words, your argument is nothing more than a slippery slope fallacy of which you have no evidence to support. Did you realize that the states with the lowest divorce rates are actually the states which have and support same sex marriage? That has not changed.
D. Appeal to tradition fallacy. Slavery was a tradition, as was denying anyone but white, male property owners the right to vote. Traditions are not inherently good or "proven" as you state. They are simply an established attitude or practice.
A. Yes. The state has the legitimate mission of continuance, survival. A nation achieves this promoting those policies which
best achieve that end, discouraging that which detracts.
WE, the people, desire to survive as a strong nation. Promoting strong families, the building blocks of any strong nation wanting to continue past more than a few generations, is a compelling state interest. We can easily view Europe and its demographics crisis due, in large part, to liberal policies put in place there within just the last three generations... it is more and more imperative that we do the right things. We have been so mired in going in the wrong direction, and now more than ever, need to come to that realization.
Our government does not prohibit private unions of same sex couples, we are a tolerant nation, so acceptance in many situations has been accomplished. But to press this, forcing society to fundamentally change into something that brings with it no particular benefit, thus no compelling state interest, for the benefit of less than 4% of the population, a population that is not replacing itself but must rely, and actually draw upon the others, seems more of a burden, most certainly does not promote the general welfare. With no definitive proof as to whether sexual orientation is due to nature or to nurture or any combination of the two, and as it could very well be heavily influenced through nurture, the state interest being survival and maintaining its vitality, why should the state promote policies that are determined in all probability to be in conflict with one of its primary missions of long term survival?
Answer: there is no compelling interest in so doing and many reasons not to do so.
B. You do not base policy on the exception, you base it on the rule [the majority]. Only opposite sex couplings, egg and sperm, produce offspring. While there are the few same sex parented families, in comparison to the whole, indeed out there, we must base policies on the majority. We allow this rarity in society, yet we have no reason to promote nor encourage this type of family unit. Demanding more, demanding equal status when such couplings are not the same, are not inherently equal and do not perform anywhere near the optimal for long term health of a society... that becomes a selfish need at the expense of the whole.
C. Slippery slopes can slope either way. We have thousands of years of study of traditional marriage to show what works, what does not. We have no studies of existing same sex cultures as none have survived. It is difficult to see how one, could, in fact, survive very long. But tell me, since you do not attempt to even address the major question,
upon what legal basis will we deny anybody from marrying anybody or anything? After we fundamentally change society? And do you deny that allowing everybody to do whatever they want will only lead to chaos? Whether you do or not, it would... and most people given a proper understanding that our laws will not allow you to just open the door a crack, to allow just what "you" want to come in, once open you let it ALL in.
As you know, regarding divorce same sex states blah blah, correlation is not equivalent to causation. Could be all myriad reasons for that stat, probably not underrepresented is that many people might be giving up on marriage as a whole, it being seen to be of less and less worth with dilution and ease of divorce.
D. Again, you have nothing to trump tradition, experimental societies come and go, seldom even noticed, often unheard of and forgotten to history. We have a proven system. Often smart/best to go home with the one that brought you to the dance. Again, you go with the rarities [Slavery], the exception upon which to base policy? We have the incubators of democracy with states, take it as far as you can go in the states, let the people there decide, then watch, see what happens... but to force everyone, whether they/we like it, believe in it, or not, that we must do as the minority says, would that not be rather totalitarian and a tyranny of the minority?