You’re not asking for a religious exemption. The US Constitution does not have a clause stating, “you can have free exercise of religion just as long as we approve of it.” Simply tell them you are INVOKING your First Amendment right to free exercise of religion and your deeply held religious beliefs are in conflict with the cvid shot. If they ask for a religious leader’s certification or something, explain (assuming you’re Christian) your religious leader is Jesus Christ whose certifying statement was penned in sixty-six books by forty different authors more than two thousand years ago. What you do need to request are reasonable accommodations in lieu of the shot- if you’ve been working all along with certain adjustments (distancing, mask, remote work, etc.,) your employer would be pretty hard-pressed to say they can’t accommodate you. If those mitigations are suddenly no longer acceptable to them, then they shouldn’t have allowed you to work in the first place. We have these tyrants over a barrel if we’d just stand up and refuse to be beaten down any longer.