The Bureau of Alcohol, Tobacco, Firearms and Explosives said Monday that the accelerant was poured at several locations around the church, including entrances.
Federal Alcohol, Tobacco and Firearms Special Agent Nick Starcevic says laboratory tests will determine what the accelerant was.
The blaze was set at the main entrance of the Wasilla Bible Church on Friday evening while a small group, including two children, were inside. No one was injured.
Palin, the former Republican vice presidential candidate, was not at the church at the time of the fire but visited on Saturday.