The Deco, in Abington Square, opened its doors to the public for the first time on Tuesday after a £4 million refit of the derelict, former Cannon cinema.
The art deco theatre, part of the Jesus Centre building, is operated on behalf of the Jesus Army by management company Incentive FM, but all profits go to the religious sect.
General manager Paul Scarbrow said: "It's a really good opportunity for us to open at a time when the Royal and Derngate are closed. It gives it a chance to establish and I think it can be capitalised on. We are all very excited and that is growing.
"However, there are artists that will prefer to come here and those that will want to go to the Derngate. Derngate has the history and the tradition. They are a different type of venue and we can become more flexible."
Mr Scarbrow admitted there had been little advertising of The Deco so far, but said a bigger campaign would gain momentum up to the first show at the venue in October.
He added: "I recognise the fact a lot of people in Northampton don't know we are here yet but that hasn't stopped people booking. Some have bought tickets then come to the box office just to check where we are. We don't mind that at all."
The Deco, which houses two conference suites and a 900-seat auditorium, will open with the opera Carmen in October and bookings have been taken for performances in March next year.
It is believed there will be further work to the entrance near Jessops between now and the opening to present a more recognisable front to the public.
Mr Scarbrow confirmed the theatre would not be used on Sundays so as not to clash with Jesus Army meetings in a separate hall within the building, but added this was the only condition the charity had given his company.
He said: "Basically we run the theatre for the Jesus Army but the rule about Sundays is the only criteria they have given us. They employ us so that is their right to use the building on a Sunday."
Source: Northampton Chronicle & Echo