I’ve read that the Zohar is not authentic and that Shimon Bar Yochai did not write it. Is there truth to this claim? What is the general consensus in the religious Zionist camp regarding the status of the Zohar?

Shalom, Thank you for your question. As you are probably aware, there is much discussion about the authorship of the Zohar. The general consensus in the orthodox world is that (at least) the major core of the Zohar was authored by Rabbi Shimon Bar Yochi. Exactly how those teachings of his were transmitted down the generations to us, and eventually published as we have them now is a major question. Most believe that the process of editing, as well as adding additional teaching to the core teachings, occurred over a long period of time, with many great Torah personalities adding there part to the process. There is certainly a general consensus that the Zohar is a major source of Torah, both kabbalistic and halachic, and its influence is felt strongly throughout the Torah world. I do not know of any particular "take" on this issue that differentiates the religious Zionist world from the rest of the Orthodox world at large. Blessings.