Aren't the Chances of Life Forming Randomly Less Than 1 in a Trillion?
This claim is based on the calculations of all of the millions of molecules in a single cell forming by chance. No scientist believes this is how life formed. Instead, most theories of "abiogenesis" begin with simple self-replicating molecules which could have formed naturally. It is believed that such a self-replicating molecule formed the earliest versions of DNA. After many thousands of years of adaptations, all governed by the non-random process of Natural Selection, did the first microbe finally develop.
For a more detailed explanation of the math involved, please see the article on this site titled The Probability of Life.
[ References: Probability of Abiogenisis Calculations (Talk Origins) ]