This doesn't happen much anymore. You will simply be asked to swear if you will tell the truth, whole truth, and nothing but the truth. No 'before gawd", no stupid babble. If you oddly found yourself in some backwater, you can simply state this , politely mentioning you have different values. Quakers have been doing it forever!

Ex-court reporter here. I think it’s a violation of church and state. I swore witnesses in for depositions. I said: Do you swear or affirm to tell the truth, the whole truth? More people lie than tell the truth. They are not afraid of being held in contempt for lying.