People often claim, "the theory of evolution is based strictly on observed evidence." And because evolution is based on observed evidence, belief in evolution requires no faith. But is the original claim true? The answer is no.
The traditional argument for the origin of life from an evolutionary standpoint is that at one point, the earth was full of primordial ooze, but had no life. By chance, there somehow came to be simple organisms. These organisms reproduced and eventually evolved into higher life forms. But what observed evidence explains the origin of life from an evolutionary standpoint? There is none. There is no evidence that biogenesis occurs (life coming from non-life). And in fact, there is lots of evidence against it. There have been many experiments to create life from non-life, and some of them have been able to create things like amino acids, but none have been able to create a living organism from non-living matter.
Evolution hinges on biogenesis being true. There is no evidence that biogenesis occurs. So the theory of evolution is not based strictly on observed evidence. And since a key point of evolution has no observed evidence, it seems dishonest to say that no amount of faith is required to believe in it.