Believing with faith is how humans get to a truth of any kind. That's why among 100% humans who know for a fact that black holes exist, 99.99% of them don't have the evidence. It by no means says that all claims such as existence of 'red hole', or 'yellow hole' exist. To us only the existence of black holes can stand a truth without evidence being shown to us. This is so because we rely on something else than evidence to determine a truth.
Basically, we treat the existence of black holes as a truth by putting faith in the scientists acting as the direct eyewitnesses. We rely on putting faith in those small group of humans, who we believe that they are maintaining a more direct contact with the truth itself, to reach a truth of any kind. Science is just one of the many kinds of truth.
We commonly referring to something outside of knowledge as 'fairy tales'. However humans are not omnipotent to know everything. There are always something we don't know. And the start point for us to get to know something is by believing in credible accounts of human witnessing. True fairy tales or myths are about things not lying inside our knowledge base and lack valid witnessing at the same time. It is the credibility of the info source which are actually examine instead of the evidence itself. That's how we treat black holes. We don't examine black holes ourselves, we trust our scientists instead.
We don't examine the evidence of what broadcast in our daily news, we trust our media made up of reports/journalists. Daily news are yet another kind of truth about what currently happening around our world. History is about what happened in the past around our world. Again, we trust what have been written down by historians instead of examining into the evidence. Most history don't have evidence anyway. That is, not all kinds of truth can have evidence left behind for us to examine. Science can be examined efficiently simply because science is all about something repeatable for us to examine repeatedly in infinitive number of times. Other kinds of truth may only be reached by putting faith in human accounts of witnessing.
In a nutshell, we examine the credibility of info sources instead of evidence to reach a truth. And in ancient days, you can't make it more creditable when the eyewitnesses are willing to die to testify what they said. That's basically what Christianity is!