ROB, other than false prophets of Zionism, we do not have neviim today, as you write. We do, however, have the Torah, B”H. Our gedolim have taught us that the Torah, (and not Zionism), is our sole source of guidance (and not just a “rules book”, CH”V, as some mistakenly believe).
Let’s take your attempt at humor to its obvious conclusion: if someone were to ask the great rabbi of berlin if one should commit a sin, your answer, then, would be that we don’t have neviim and so we don’t know what Hashem wants of us.
Once again, while we may not always know for certain what is the ratzon Hashem, there are many times when it is quite clear what is or is not the ratzon Hashem and others that may require a sheilas chacham, etc. to determine the Ratzon Hashem there. You love to quote (when it’s convenient for you, of course) Yiftach biDoro kiShmuel biDoro.