The letter was distributed across the Archdiocese of Adelaide, including to parents of students in Catholic schools, drawing criticism from some.

It confirmed his intention to stand aside from his role on Friday after putting in place the "necessary administrative arrangements" to ensure the affairs of the archdiocese are managed responsibly.

"I know we are a united community of believers, a people of hope, and we will continue to be the disciples of Jesus," the 67-year-old wrote.

"We have achieved great things in all facets of the life of the archdiocese, including in our parishes, schools, social services, health and in aged care."

Wilson said he wanted to assure the Catholic faithful of his "continued prayers and best wishes".

"Please continue to pray for me," he wrote.

Some people took to social media to criticise the letter, particularly its failing to mention the victims of abuse.

On Tuesday, Wilson was found guilty at Newcastle Local Court of failing to report to police the repeated abuse of two altar boys by pedophile priest James Fletcher in the NSW Hunter region.

He is the most senior Catholic official in the world to be charged with concealing child sexual abuse and faces a maximum two years' jail.

In a statement issued by the Catholic Church on Wednesday, Wilson said it was appropriate to stand down in light of Magistrate Robert Stone's findings.

"If at any point in time it becomes necessary or appropriate for me to take more formal steps, including by resigning as Archbishop, then I will do so," he said.

He is still considering Mr Stone's reasons alongside his legal advisors.

"In the meantime, while the remainder of the legal process runs its course, I want to assure the Catholic faithful in the Archdiocese of my continued prayers and best wishes and assure everyone that the affairs of the Archdiocese will be appropriately managed in my absence," the clergyman said.

Australian Associated Press