Answer: they both require a great leap of faith - it's just that the theists are more honest about it.
Moreover,
Many have noted that this fine-tuning strongly suggests design by a pre-existent intelligence. Physicist Paul Davies has said that “the impression of design is overwhelming.” Fred Hoyle argued that, “A common sense interpretation of the facts suggests that a superintellect has monkeyed with physics, as well as chemistry and biology.” Many physicists now concur. They would argue that — in effect — the dials in the cosmic control room appear finely-tuned because someone carefully fine-tuned them.
To explain the vast improbabilities associated with these fine-tuning parameters, some physicists have postulated not a “fine-tuner” or intelligent designer, but the existence of a vast number of other parallel universes. This “multiverse” concept also necessarily posits various mechanisms for producing these universes. On this view, having some mechanism for generating new universes would increase the number of opportunities for a life-friendly universe such as our own to arise — making ours something like a lucky winner of a cosmic lottery.
But advocates of these multiverse proposals have overlooked an obvious problem. The speculative cosmologies (such as inflationary cosmology and string theory) they propose for generating alternative universes invariably invoke mechanisms that themselves require fine-tuning, thus begging the question as to the origin of that prior fine-tuning. Indeed, all the various materialistic explanations for the origin of the fine-tuning — i.e., the explanations that attempt to explain the fine-tuning without invoking intelligent design — invariably invoke prior unexplained fine-tuning.
To explain the vast improbabilities associated with these fine-tuning parameters, some physicists have postulated not a “fine-tuner” or intelligent designer, but the existence of a vast number of other parallel universes. This “multiverse” concept also necessarily posits various mechanisms for producing these universes. On this view, having some mechanism for generating new universes would increase the number of opportunities for a life-friendly universe such as our own to arise — making ours something like a lucky winner of a cosmic lottery.
But advocates of these multiverse proposals have overlooked an obvious problem. The speculative cosmologies (such as inflationary cosmology and string theory) they propose for generating alternative universes invariably invoke mechanisms that themselves require fine-tuning, thus begging the question as to the origin of that prior fine-tuning. Indeed, all the various materialistic explanations for the origin of the fine-tuning — i.e., the explanations that attempt to explain the fine-tuning without invoking intelligent design — invariably invoke prior unexplained fine-tuning.