That light is the theft deterrent indicator. This will prevent engine starting, the system works by watching the ignition lock cylinder to make sure it's rotating. There is a sensor/module attached to it, called the passlock module, and this module has to send a password ***** the engine computer to allow the engine to start.
The problem with this system usually has to do with wire connections. They degrade over time, allowing voltage drop that changes the signal from the module. Typically, you can do a relearn on the system, the computer will adjust to this voltage drop, and you can go forward without issues. I'll give you the procedure to relearn it, and we'll see if that gets you going.
Attempt to start engine, leave key ON. Security light will be on, leave key on for ten minutes, until the light goes out. Then key off, then attempt to start again, leaving key ON. Wait another ten minutes until security light goes out, then key off, and try to start it a third time, leaving key on for another ten minutes until light goes out. After this 30 minute procedure is complete, key off, and attempt to start. Engine should start and run if the procedure is successful.