The coronavirus pandemic has forced the Baptist Union of Great Britain (BUGB) and Church of Scotland to call off their upcoming General Assemblies.
The BUGB said its General Assembly was postponed, while the Church of Scotland has cancelled its event entirely.
Both were scheduled to take place in May.
Prince William had been due to address the opening session of the Church of Scotland General Assembly on May 16 in his role as Lord High Commissioner, representing the Queen.
Announcing the cancellation, Principal Clerk, Rev Dr George Whyte, said that people's health had to come first.
"We did not take this decision lightly but in the current circumstances it was the only choice we could make. Our Assembly would have brought almost a thousand people to a week-long meeting in Edinburgh including visitors from overseas and from other churches," he said.
"It is a time when we can celebrate being the Church and make important decisions about our future but these are exceptional times and people's health must come first.
"We were also looking forward to welcoming the Duke of Cambridge as the Queen's representative but we are assured that Prince William will understand our unavoidable decision. We hope that he may be Lord High Commissioner on another occasion.
"In the meantime the Church will find alternative ways to make urgent decisions including confirming the appointment of our new Moderator, the Rev Dr Martin Fair, who will take up his duties in May."
The BUGB's General Assembly was originally planned for Bournemouth, from 8 to 10 May, with Shane Claiborne among one of the guest speakers.
It has postponed the assembly until the autumn and promised refunds to those who booked tickets for the May gathering.
"We are very sorry to announce that the Baptist Assembly has been postponed until the autumn, due to the coronavirus. We will make an announcement about the new dates as soon as we can."
