Well, first of all, obviously vaccines don't cause autism, all the evidence has proved this over and over again. Besides, if it was caused by vaccines it couldn't be heritable, and it is (though not entirely). And kids still get autism even now that there's no mercury in the vaccines. Sorry, find a new scapegoat.
But even beyond that-- let's assume the autism really was caused by vaccines. Autism is a) non-contagious, b) non-deadly, and c) present in a spectrum, with most people within that spectrum perfectly capable of living a reasonably successful or normal life, although they're not really socially adept (neither am I, and I survive). Full blown autism is only about one in 1000 people. So in our hypothetical scenario, there is only a 0.001% chance that getting a vaccine will result in an autistic child.
Compare to the alternative, not getting the vaccine. Let's look at the DTP vaccine. Diphtheria has a 5-10% fatality rate in children under 5 years and a 20% fatality rate in adults over 40. Before the vaccine was invented, a person had a 0.002% chance of getting diphtheria. Also, diphtheria is a heck of a lot worse than autism (not that autism isn't horrible, but at least it doesn't involve open sores). And that is a single disease; things like pertussis, measles, and whooping cough add to the chance that an unvaccinated person will get SOME horrible illness. I mean, unvaccinated children living in our modern, vaccinated society manage to get polio, despite the fact that the virus can't easily perpetuate in a population that is immune to it.
So even using the false hypothesis that vaccines cause autism, it's STILL better to vaccinate, because an unvaccinated child has a greater chance of getting an illness that can be prevented by vaccines than a vaccinated child would have of getting autism. Also, most illnesses that vaccines prevent are far, far more painful, dangerous, and deadly than autism is, even at it's absolute worst.
I'm not a huge fan of over-vaccination, which I define as vaccinating against things that aren't actually going to hurt you too much in the long run, like chickenpox (well, unless you're in your teens or older and never had it as a child), or things that could hurt you, but your lifestyle, age, and/or health make catching a bad case unlikely (like influenza for me, but not for my best friend, who often works with individuals who are high-risk for catching it).
But to prevent polio, diphtheria, rubella... there is no excuse for not vaccinating children against those illnesses. Not even religious objections (will God really stop a person from entering Heaven just because they got a shot? Wouldn't it be a worse sin to not get a shot, and catch and spread the illness, killing yourself and another? And can't you atone and describe yourself as some kind of martyr who was forced into it, anyway?).
Certain vaccines are a public health concern, they should NOT be optional. Even if it meant I had to take a flu shot every year, I'd support legislation that would force all parents to vaccinate their children without exception. If they object, force them to watch a movie about Typhoid Mary. When it comes to serious infectious disease, the government has a duty to restrict the rights of it's citizens enough to protect other citizens, and the more people we vaccinate against a disease, the more likely that disease will go the way of smallpox, no one will ever be at risk again, and we won't need the vaccine any more.
The only reasonable and safe way to stop the widespread vaccination of children is to continue it, even increase it, until it is no longer needed at all. Period.