Bolded phrase is nonsensical, unless posited as an unfalsifiable axiom. Explosions aren't low-entropy, and you're probably referring to the state of a tightly packed, super-dense cluster of matter before it exploded. But how did that super-dense cluster get there in the first place? Where did the material for the Big Bang come from?
I think you'd be better off trying to argue an example of high-to-low entropy with something like gravity and the formation of galaxies, solar systems, planets and stars, etc. Or rather, argue that these aren't actually examples of low entropy, but that these, and life, are actually just high-entropy systems bounded by chemical interactions.
That puts you more in the range of smarter atheists.
But if there's one question I've always stumped atheists with, it is the question: "Can you trust that the sun will come up tomorrow morning?"
That is, can you trust the laws of the universe to remain constant? Every law, even physical laws, have two essential characteristics: they have a Giver and an Enforcer. Without a Giver, a law cannot exist. Without an Enforcer, a law is meaningless. Laws must be Given and Enforced. Every atheist I have encountered cannot describe a Giver nor an Enforcer for the constraints of our universe. But yet, such a belief is necessary for science to mean anything, because science is predicated upon the consistency and predictability of the universe, even of time itself; yesterday is always yesterday, today is always today, and tomorrow is always tomorrow. In the Christian God we are assured of this truth. But atheists can only fall back on personal experience, but even that is suspect in an atheist universe where there is no assured enforcement of the constraints of the universe. How can you be sure that yesterday ever existed? You say you remember it, but what if you just blinked into existence a moment ago with false memories?
I also find myself having to ask: why are the laws so specifically designed to ensure that an universe could exist at all?
Atheists reply with the anthropic principle, but I reply: that is circular reasoning, you are arguing that there is an atheistic explanation for the universe because we exist.
-Didn`t say I was an atheist (I like bold writing to underscore a point)
-Fine-tuning (both in terms of stable universes and life within them) could be explained by many processes, like multiple universes, where only a very few can harbour life. And maybe an evolution of universes also. Of course we don`t know where matter comes from, but that could mean many things, including that God brought it into being.
-I did argue that the formation of galaxies, solar systems and the distribution of matter where related to the forces/laws of the universe, and that those things where a consequence in part of the uneven entropy "scattering" that would then take place over eons of time post big-bang. Life would then be a microphenomenon related to the same process. Think of the whole thing as one big movement that lasts for billions of years, but that is very dynamic still.