If you condition on "a foetus is as valuable as a baby", which is something that a lot of people believe...
Then even if you accept that to deny abortion is to curtail women's liberty, and this is bad, so that preventing abortion is not an unmitigated good...
And even if you accept that allowing gay marriage is an unmitigated good...
Then it still seems to me like abortion is a much more pressing issue than gay marriage. It's a trade-off, but that doesn't mean the answer isn't obvious, and it doesn't mean that a good thing which isn't a trade-off will necessarily be more valuable.
(There are three "if you believe..." statements in this post. I want to make it clear that I'm not endorsing or disendorsing any of those beliefs.)
Then even if you accept that to deny abortion is to curtail women's liberty, and this is bad, so that preventing abortion is not an unmitigated good...
And even if you accept that allowing gay marriage is an unmitigated good...
Then it still seems to me like abortion is a much more pressing issue than gay marriage. It's a trade-off, but that doesn't mean the answer isn't obvious, and it doesn't mean that a good thing which isn't a trade-off will necessarily be more valuable.
(There are three "if you believe..." statements in this post. I want to make it clear that I'm not endorsing or disendorsing any of those beliefs.)