Attempts (like the thread OP), to assert a belief is validated by insisting alternative evidence or explanation is demonstrated, is using a known common logical fallacy called argumentum ad ignorantiam.
Epistemologically, no responses is even necessary, it’s logical to dismiss any such fallacy.
Hitchens’s razor applies.
However, when theists assert that a supernatural cause from an unevidenced deity is more probable, than some as yet unknown natural phenomona. Then we should note some contrary facts to their claim.
- They cannot demonstrate that a deity or anything supernatural is even possible, let alone show how probable it is.
- Natural causes have been demonstrated to exist, so we know they’re possible, and we know there are natural phenomena we don’t yet understand.
- Since extant natural causes are a known fact, and supernatural causes unevidenced wishful thinking, to rule out the former as less probable than the latter is risible bias.
- Never forget religions have done this for many natural causes when we didn’t understand them, and have had to be dragged screaming to accept those facts as science uncovered them, some theists still deny known facts like evolution in favour of unevidenced superstition.
As @Calilasseia has pointed out above, the dishonest attempt by the thread author to conflate abiogenesis with atheism should have alarms bells ringing, as it amply shows the logical fallacy behind the duplicitous assertion.
Atheism does not need to explain anything, anymore than not believing in garden fairies requires evidence.
Some theists like to load the dice in their favour, because at some level they know they’re holding an empty bag, and don’t want to focus on that fact.
Other theists are simply ignorant of the most basic logical tenets, and use simple common logical fallacies because they are ignorant of them, and what their use means. Often ironically, while simultaneously claiming such arguments are rational.