An Indiana state trooper who was fired from his job for proselytising to a motorist does not regret his action, saying he is a "soldier for Jesus Christ."

Former Indiana State Police senior trooper Brian Hamilton was fired from his job on Thursday for insubordination and neglect of duty after he preached to a motorist he stopped for traffic violation last January.

A complaint was filed by Wendy Pyle against him, which led to an investigation that found him in violation of a 2014 agreement that prohibited him from proselytising while on duty.

Following his dismissal, Hamilton was seen on Saturday preaching to people on the street in Connersville, Indiana.

"They came out for the Lord Jesus Christ, they didn't come out for me. They came out to exalt the name of Jesus and they know what the truth is, and they know that the only way anybody can be changed is to the name of Jesus, and they know that they need to be obedient to Christ when Christ tells them to do something, as a soldier for Jesus, they're going to stand up," he told the crowd, 6ABC reports.

Pyle said when Hamilton stopped her and gave her a warning ticket, he asked her about her faith and told her about his church.

Hamilton refused to comment on the charges by the Indiana State Police but said he is a soldier for Jesus Christ.

"When I got saved three years ago, it changed my life, and I know what you're all doing here for and I can't really comment on the allegations of the state police. And I was a former state trooper, but I always said after I got saved, I said I work for the state but ultimately, I'm a soldier for Jesus Christ," he said.

Hamilton said God used his job as a state trooper in the last three years "to spread the Word, to tell people when they're hurting, the truth. Government programmes cannot touch anybody, it's the Word of God that can change people."

The American Civil Liberties Union of Indiana has also filed a complaint on behalf of Pyle against Hamilton.

Hamilton was first sued in 2014 when he stopped a motorist and asked her about her faith. The lawsuit was settled.

Indiana State Police Superintendent Doug Carter said while everyone enjoys "the right to freedom of religion and freedom of speech, there are appropriate and proper restrictions placed on agents of the State related to their actions while engaged in their official duties."

Carter wished Hamilton "the best in his future and the ability to follow his heart."