The shooting happened after a fight inside the building on Sunday.
An investigation has been launched into the conflict, that started during the 11am service at Keystone Fellowship Church.
At least one shot from a semiautomatic handgun was fired. Investigators say the person suspected of firing the gun was also a church member.
Congregation member Robert Baxton, 27, died after receiving a shot wound to his chest, police said.
He was taken to Abington-Lansdale Hospital where he was pronounced dead at 12:11pm.
An autopsy is expected to take place on Monday.
Speaking to NBC10 Breeana Somers, who was inside the church at the time of the shooting, said: "It sounded like three pops, almost like a champagne bottle opening three times."
She continued: "Everybody's trying to make themselves as small as possible. You could hear some screaming and some crying but it was pretty silent. I went under a chair in a foetal position. I tried to make myself as small as possible. It's really frightening that anything like this could happen here."
Police arrived at the church around 11:23am.
The other person involved was also taken to hospital and later released.
The man is cooperating with the police and no charges have been filed according to investigators, who say they are trying to examine whether the shooting was justified.
They added that the male had a permit to carry a concealed weapon.
Montgomery County District Attorney Kevin Steele told NBC10: "There's no one in custody.
"The individual involved in the shooting is cooperating with police at this point."
It is thought that the shooting happening in the church sanctuary when hundreds of people, including children, were present.
The church released a statement in a Facebook post confirming the shooting.