"He's a very decent young man who is simply exercising his First Amendment right of speech," Gibbs said Saturday.
Grant tweeted after the arrest that the officer had accused him of solicitation. Gibbs said Grant had been talking to people and taking photographs with them, as he has done for months in the LOVE Park area.
Grant accepts tips, he wrote on Twitter, but does not actively seek money.
The officer told Grant to leave the area, but Grant did not, Gibbs said, because it was "an unlawful order to leave a public park."
Philly Jesus was then arrested.
He believes the officer recognized him from the time, more than a year ago, when he was homeless, addicted to drugs, and would panhandle in Suburban Station, Gibbs said.
Court records show that Grant has been arrested more than a dozen times on charges including loitering, possession of marijuana, and theft of services.
"He believes that the officer remembers him from those days," Gibbs said, adding that Grant has been sober and drug-free for a year.
Grant has been retweeting dozens of supportive messages from his flock of Twitter followers.
His lawyer said Grant was looking forward to his day in court. In the meantime, he said, Grant will continue to spread his message.
"To have our local government try and crucify a guy who's standing in LOVE Park and spreading a message of hope and peace is reminiscent of what happened 2,000 years ago - and still patently disturbing," he said.