I would only disagree in that a 'certified letter' is sufficient for legal purposes. Registered mail is for when you are shipping irreplaceable valuables. Certified mail is for legal documents. It contains proof of delivery and can be done to require the addressee sign for it.
Registered mail is used by lawyers and attorneys every day.
It's a delivery system that has all points of handling the correspondence or parcel signing receipt of said correspondence or parcel.
The final receipt,to whom it is addressed, must show ID to the carrier and sign for it.
Not always the case with certified mail.
Though if someone wants to go that route there is the $added option of ''restricted delivery adult signature's. However I know enough carriers to know they don't often ask for ID in that case. And anyone at the address may sign for the correspondence or parcel.
If someone does go with certified mail make sure you add the option , return receipt requested. This way you have that much evidence the letter was received. Though there's no guarantee someone has signed for it on that receipt. Which is not the case with Registered mail.
Whereas Registered mail necessitates the addressee must show valid ID to receive the letter.
You want that proof in a case like this because it proves on your end that you went through the proper steps to inform the addressee of your wishes.
Make sure you have a copy of the letter, and being you have to fill out the Registered mail paperwork,ideally, at the post office, use your phone. Take a picture of the letter and the registered letter tag with it. This way you have proof the registration number on that mailer accompanied the letter itself.
Some people in order to wiggle out of responsibility for receipt of a registered letter have argued the letter they received was not what was mailed according to the Registered mail receipt.
If this gets out of hand you want as much proof as possible to support your demand that pastor cease and desist their harassment of you.
Make it a cordial but direct letter. And date it. If they persist after that, keep all correspondence with their return address in tact.
Don't open it. Wait, and see if you receive another one. Same thing. Don't open it. Then, contact an attorney. Make sure the post mark is visible on those letters should they arrive after you send the cease and desist letter.
You want clear proof those correspondence arrived after you sent the cease and desist letter.
Part of the reason for the Registered letter is the date of correspondence, and its receipt by the addressee.
When they sign and date after showing ID you have proof of receipt of your demand letter.
No, that doesn't insure they read it. However, that's outside your control.
What sustains your part in levying the command to stop contacting you is that proof you sent a letter to that effect. And their signature proves they themselves,with ID, took custody of said correspondence on a certain date.
They shouldn't write you back after receiving the cease and desist letter. Because that is contrary to the demand.
Stay safe.