A group of masked men carried out the attack, police said.
Malcolm McKeown was shot dead on Monday 19 August.
Both men were arrested following searches in the Lurgan and Craigavon areas of Armagh.
Police described the attack as a “vicious assault”.
24 petrol bombs and six paint bombs were also thrown in the streets.
Police believe the incident was staged to lure officers to the area.
Six properties were searched by the PSNI across Belfast today.
The PSNI said they commonly receive reports of fraud.
Loughinisland journalists: It’s still surreal to think we were arrested in Northern Ireland for a documentary
“Police officers were going through our computers, and taking documents that were completely unrelated to the film.”
The PSNI officer is said to be “very shaken and distressed” after the incident.
Two men are believed to have started the blaze at Holy Family church at 10.30pm.
A young child who was in the house at the time was not injured.
Lisa Dorrian disappeared after a party at a caravan site 14 years ago.
In 2010 Cahill alleged that she was raped by an IRA member when she was 16-years-old.