Hi, Shannon. You are about to start on a tough job and find out one reason why most of us on the board don't think much of painted brick. The best product for this is called Peel Away. It is a lye based stripper that you put on the brick with a brush, cover with a sheet of their material that keeps the stripper working for a day or 2, then remove it. Contrart to the name, Peel Away will mostly come off when you remove the sheet but you will have to get ther rest out of all the little cracks and crevises in the brick. You get the rest out with a cheap, wood handled, hand wire brush, putty knife, dental tools and any other small tools that you can think of and will work on your particular brick. Be very careful if you use the wire brush as the wire can fling the lye in unexpected directions and it is not good for you, your skin, wood, fabric. Vinegar will neutralize lye, by the way, so have a gallon of cheap white vinegar and some rags handy, just in case. Be very sure to wear chemical resistant rubber gloves and eye protection. If you use the wire brush, also wear a full face shield (available at industrial tool supply stores and woodworking stores for about $20).
Peel Away is available at Woodcraft stores and mail order. It is also available at some home centers but I would try to find a local paint store that can get it. There are several different formulations and they will work with you to choose and obtain the best one for your job.
I want to stress again, be very, very careful with the Peel Away. Follow all the label directions.