The pastor of the First Baptist Church in Villa Rica, Georgia, has responded to a group of atheists who denounced the mass baptism of the football coach and players of the Villa Rica High School, asking: "When did it become illegal to bow your head and pray? When did it become illegal to say I'm a Christian?"

The atheist organisation Freedom From Religion Foundation (FFRF) verbally bashed the school after a video posted online last month showed the coach and players getting baptised before a football practice inside school property, claiming that the act was in violation of the First Amendment of the US Constitution.

About 75 people gathered to watch the coach and football players of the Villa Rica High School get baptised by the First Baptist Church, according to Fox News.

FFRF sent a letter to the Carroll County School Superintendent Scott Cowart to point out the alleged illegal action.

"It is illegal for coaches to participate in religious activities with students, including prayer and baptisms," FFRF staff attorney Elizabeth Cavell wrote. "Nor can coaches allow religious leaders to gain unique access to students during school-sponsored activities."

She added, "When baptisms and prayer take place directly before a team football practice, on school property, with coaches' participation, any reasonable student would perceive these activities to be unequivocally endorsed by their school."

The FFRF said the district should investigate this and take action.

Responding to the complaint, Kevin Williams, the pastor of First Baptist Church, said the baptism was voluntary. "We never meant to cause any problems for the school and we never thought we would get this much media attention for baptising kids," he said.

The church held a football-themed worship service called "Gridiron Day," an event in which a coach asked the church if he could be baptised on the football field.

"It was their choice to do that," Williams said. "We live in a free nation. People choose what they want. These people that got baptised freely chose at a church service to accept Christ and this was a follow-up to that."

The pastor noted that for the past few years, several teenagers have committed suicide in Villa Rica amid "tough times" in the city.

"We're trying our best as a community to reach out to these kids and love on them and show them there's a better way—there's hope," Williams said. "That's what we are providing through Jesus Christ to these kids."

Williams said he believes that "we live in a free country."

"These people that are trying to say you can't do that—well—they're taking away freedom. When did it become illegal to bow your head and pray? When did it become illegal to say I'm a Christian?" he said.