seems like the cheap way out, to point to a phenomena that is not completely understood, and exclaim, "God!!" doesn't it?
imagine if you took a tv or a cellphone back to galileo. at first, he'd be astounded, and might think (and not without good reason) that he was seeing something supernatural, that could only be the work of God. But with proper explanation, a smart man like galileo would eventually be able to understand the workings of advanced objects. I don't see any reason why that can't be the case with the things you mentioned.
quantum tunnelling does not really need to be 'deciphered.' even though QM is an incomplete theory, it explains tunnelling pretty exactly: it's all probability.
it's certainly NOT impossible to discover life elsewhere. What will you say if we find a signal from a faraway star or even microorganisms in the oceans of Europa?
and as for Why, well, Why is just a word. Why doesn't need any explaining. Why is a concept that humans invented. Why is there a galaxy 700 kpc from us? Why do quarks have charge?
they just do/there just is. there is no why.