So your argument is basically "don't do it, because what I believe in is more probable than what you believe in" even though there's no way to calculate those probabilities.
No, my argument is that there is no moral standard regarding this issue, that the majority on this planet agrees with, that there is no legitimate interest or ownership that could force anyone from doing otherwise, and that the potential benefits (colonization, resources, space) outweigh the belief in something that might be on Mars.
Meanwhile your argument is based beliefs where you can't even possibly calculate a probability, just like the belief in god.
What we have is our tools and capabilities to try and work with what we can reach at the moment in our solar system.
