How does the Wall in The Handmaid's Tale link to religion?

Of the various figures that appear hanged on the wall, some are religious figures. Priests and nuns are enemies of the state as they represent an active resistance to the religious doctrines that characterize the official views of Gilead. 

In Chapter 6, Offred and Ofglen walk to the Wall and first pass by a small church. 

"Now we we turn our backs on the church and there is the thing we've in truth come to...

Of the various figures that appear hanged on the wall, some are religious figures. Priests and nuns are enemies of the state as they represent an active resistance to the religious doctrines that characterize the official views of Gilead. 

In Chapter 6, Offred and Ofglen walk to the Wall and first pass by a small church. 

"Now we we turn our backs on the church and there is the thing we've in truth come to see: the Wall."

The detail here is suggestive. While standing near the church, Offred and Ofglen do not move to go inside but instead look at the gravestones. Religion and death and the Wall are thus linked subtly.

In turning away from the church Offred and Ofglen find more signs of death when they see people hanged from the Wall. Later in the novel these figures are discussed to include religious figures opposed to the new state religion.

The state of Gilead, arguably, has turned away from this older mode of religion represented in the church Offred is visiting in order to embrace a new one. 

"They haven't fiddled with the gravestones, or the church either. It's only the more recent history that offends them."

As a totalitarian regime, the state of Gilead suppresses all sects and belief systems that do not directly support the official dogmas of the government. Only cooperation is acceptable. Only full acquiescence is deemed appropriate. 

The Wall helps to define this harshly enacted policy by placing subversives dead on display. 

"What we are supposed to feel towards these bodies is hatred and scorn."

The state communicates its policies through public violence on the Wall and elsewhere as a means to reinforce conformity and to suppress any resistance. As a religiously-oriented political body, the state's enemies naturally include competing religious views and so priests are sometimes found hanged on the Wall.