[WingForward]

Actually, people in the time of Columbus knew the the Earth was round. That's been in European cultural knowledge for about two thousand years. It was Columbus who was mistaken. He thought the earth was much smaller than everyone else did. That he could sail west to Asia in a few weeks. He was completely wrong. A fool who was funded by a fool.

But you're right, in that they had as much evidence as you have about Mars. As in, with a some hours of observation, you too could establish that the Earth is round and that Mars is a planet and know as much as a 15th century nobleman. All from first principles. You just need to view the evidence.

That's different than religion and "faith". Those don't require evidence. In fact, faith require the absence of evidence.

You can try to equate evidence-based beliefs and non evidence-based beliefs, but they are not the same.