1998 Pontiac Grand Am won't start

I blew the motor in my car, I've replaced it with a long block and have reused all of the externals, fuel rail and injectors, alt, coil and such. I'm getting fuel to the engine but it won't start. The anti-theft light is on when I crank it over and don't remember it ever being on before. I was a fair mechanic before the computer controlled cars came along. What am I missing, with the coils under the plate above the plugs it's hard for me to check if there getting spark. I'm at my whits end with this car, is it a security issue with it. Thanks for your help