If the cat was glowing red then it is trashed and needs to be replaced. Whether or not the engine has been permanently damaged or not depends on how long it was driven that way.

 

I just replaced the catalytic converter. The new cat was glowing red.

 

Did you check the exhaust before installing the new cat to make sure that old cat material was not blocking the exhaust path? Was this a new OEM cat or new to you? Also double check your firing order and make sure the plugs, wires, and coil wiring are secure.

 

(Just don't cut open the cat then reweld it to check if it's good.)