The only reason evolutionists are claiming this today is that they’ve been unsuccessful — without massive intervention by intelligent design provided by abiogenesis researchers themselves in the laboratory — in demonstrating how a living, self-replicating organisms (such as a cell) could have formed by itself, by means of purely physical forces, plus lots of time.
The two best books on this subject are long out of print but still available if you search for them: “The Mystery of Life’s Origin: Reassessing Current Theories” by Charles Thaxton, et al.; and “The Creation of Life: A Cybernetic Approach to Evolution” by A. E. Wilder Smith. Among other things, they both show that all theories of abiogenesis violate the 2nd law of thermodynamics, as well as violating its statistical-mechanics interpretation (i.e., left to themselves, systems always move from configurations of lower probability to configurations of higher probability; that’s why things decay; that’s why a nice straight wall made of brick and mortar (a low-probability configuration for clay and mortar to take) always, over time, turns into one of many possible piles of rubble (one of many high-probability configurations clay and mortar can take). I’ve never seen any intelligible response from abiogenesis enthusiasts to this objection.
Additionally, there are mathematical coding-theory objections to many abiogenesis scenarios: i.e., since 64 possible codons in DNA/RNA represent, or map to, 20 amino acids that build various proteins, the 64-symbol alphabet must precede the 20-symbol alphabet; i.e., you can map 64 symbols onto 20 symbols (with redundancy), but you cannot map 20 symbols onto 64 symbols (without ambiguity, which is the death of the code system). So a “proteins-first” scenario is mathematically impossible; i.e., DNA would (mathematically) have to have appeared first, followed by protein synthesis. The problem here, however, is the DNA itself requires the environment of a pre-existing cell (with all of its proteins) in order to function. I’ve never heard any intelligible response by abiogenesis enthusiasts to this chicken-egg paradox between DNA and proteins.
Finally, there’s another basic coding-theory problem that remains unsolved by abiogenesis: in order for a code to function as a code, both the sender and receiver must have PRIOR knowledge of what the code means, i.e., what the code is supposed to code for, and how it is supposed to be decoded. In the case of the living cell, both the DNA molecule and the ribosome must have “communicated” with each other in the distant past in order for both of them to “understand” the same code, i.e., that 64 possible 3-letter arrangements of nucleotides represent 20 possible amino acids that can be combined into many different polypeptide (proteins). This, too, remains unsolved... and perhaps unsolvable by purely naturalistic, material explanations.
On a related but much simpler note, didn’t you ever wonder where “instincts” come from?
Instinctive behavior is software, even if it’s hardcoded into the mechanism. How do you get software without a decision, a concept that is anathema to natural selection?