1) metaphysical properties
Many living beings, especially humans, have properties that cannot be described physically (if we are evolved by the action of some natural agents then we are nothing but chemical/physical equations). How do we explain the metaphysical properties like love, consciousness, empathy, life etc. ? Evidently, they originated from a metaphysical entity we call, God. If God acted at some phases of our life, it is natural to believe that God is the cause and designer of the life.
2) Complex, cumulative, well defined product.
A complex, cumulative, well-defined product posits predesign so, Intelligent Design is the default explanation of the life. Why do we assume that some natural agents like environmental changes ,"survival of the fittest" etc. would result into this many complex species? Where did their instincts come from ( why do baby turtles move towards the ocean right after they are hatched ) ?
No one bothers to explain why the leaves are scattered randomly after a storm nonetheless, if there is a pattern or discipline in which the leaves are arranged, the involvement of an intelligent mind is all but certain. No objects can escape a universal cause unless it is acted upon by an external agent. It is the disorder among physical objects that increases with time so, if we see the order increased over the time - more complex species appeared over the time - then the involvement of an intelligent mind is certain.
3) Origin of life.
Origin of life is arguably the most complex event known to humans. It is so complex that some scholars believe the early forms of life like Amino acids or Protein molecule came from outer space. The life originated at the time when Earth was hostile to living forms, with harmful radiations, devastating tornadoes, earthquakes etc. For most part of Earth's existence, Moon's gravitational field caused frequent tsunami's. Yet, the primitive life not only thrived but it advanced to more complex forms. Doesn't this prove the involvement of an intelligent mind?
4) Male and female.
What sort of "natural agents" mutated the primitive bacteria, presumably unisex, into complex male and female with organs which complement each other? Not to mention, their instinct to live together and reproduce.
5) Irreducible complex.
Two well placed eyes and ears are required for estimating the distance of the source. Just curious, did the earliest species to have eyes and ears had them at random places and only those with the organs correctly placed survive?