Saints started the day 10 points clear of the bottom but despite battling back brilliantly to share the spoils, their fate remains uncertain after basement club Dundee defeated Hearts 1-0.
But after twice trailing, with Leigh Griffiths again starring for Hibernian, the visitors should be applauded for their spirited recovery.
Griffiths opened the scoring by firing in his 26th goal of the season with a stunner from 30 yards.
Back came Saints as Esmael Goncalves levelled on the hour by squeezing the ball past keeper Ben Williams.
It was time for an inexperienced teenager to take to the stage as 19-year-old Ross Caldwell came off the bench to get the hosts back in front again a minute after coming on the pitch.
Scoring his first-ever goal in senior football was a mighty effort, only for Marc McAusland to steal the show.
His header made it 2-2 after a messy scramble and he then nodded in again to give his team the advantage for the first time from Gary Teale's cross.
Hibs though were not to be denied as Griffiths secured his double to leave this enthralling contest on level terms.