Despite some remaining puzzles, there's no reason to doubt that Darwin had this point right, that all creatures on earth are biological relatives

In the abstract, it might be tempting to imagine that irreducible complexity simply requires multiple simultaneous mutations - that evolution might be far chancier than we thought, but still possible. Such an appeal to brute luck can never be refuted... Luck is metaphysical speculation; scientific explanations invoke causes.

There is no publication in the scientific literature - in prestigious journals, specialty journals, or books - that describes how molecular evolution of any real, complex biochemical system either did occur or even might have occurred.

Although Darwin was able to persuade much of the world that a modern eye could be produced gradually from a much simpler structure, he did not even attempt to explain how the simple light sensitive spot that was his starting point actually worked.

The basic structure of proteins is quite simple: they are formed by hooking together in a chain discrete subunits called amino acids.

I believe the evidence strongly supports common descent. But the root question remains unanswered: What has caused complex systems to form?

Science is not a game in which arbitrary rules are used to decide what explanations are to be permitted.