Pro life is a bit murkier then SSM. If you believe abortion is the same thing as murder then you have a stronger arguement no doubt then a person against SSM.
While I think pro-life and anti-SSM are BOTH strong arguments, I would tend to agree with you on the overall point. The pro-life argument is incredibly strong, and the only people who challenge the position want to change the nature of the debate (to make it more about choices than about life, which is why the term "pro-choice" is used rather than "anti-life", well, that and the fact that "anti-life" is terrible from a public relations standpoint).
Compared to the rock solid nature of a "pro-life" argument, an anti-SSM position is naturally the weaker of the two. It's based upon personal beliefs and tradition rather than what necessarily makes the most logical sense. Still, personal beliefs and tradition are things that matter to people, and as such they must be considered in any argument over what the government should do regarding the matter.
I cant believe you are comparing gay people to trees and bridges.
I'm not. I'm comparing one reason people want to change the rules of marriage to another potential reason.
Do you not understand the difference between a sentient being and an inanimate object?
Certainly I do. But we have to draw the line somewhere. Why are we drawing the line immediately after SSM? Why not before that (with just heterosexual marriage) or further down the line (by allowing people to marry trees, bridges, etc.)?
The reason is because the homosexual agenda benefits from a decision to draw the line where you suggest, and that's all that matters to them.
drinking harms countless thousands every year, smoking harms countless millions.
Yes, and I think there need to be much stronger laws against those things and the harms they cause.
I think taxes should be increased to incredible amounts on tobacco and alcohol. If people are going to do stupid things they're going to pay society back for some of what they cost it.
I think getting a DUI (or DWI) should be a felony even on the first time, and I favor the death penalty for anyone who kills someone else while driving drunk. In fact, I think the relatives and friends of the deceased victim should get to choose the method by which they drunken fool gets killed, and it should be televised to discourage other drunken idiots from getting behind the wheel.