The security system doesn't stop the starter from cranking, it stops the fuel pump from running once the vehicle's started.
Your problem is more likely with the starter motor or the ignition switch itself.
If you're thin and flexible, you can shimmy under the front end and wang on the starter motor with a hammer while someone tries to start the Jeep. If that works, you need a new starter.
Does anything at all happen when you turn the key to the start position? If the switch is good, the interior and should go out, all the dash lights should come back on for a check, the usual.
2006 WK Laredo 4x4 4.7L
1993 ZJ Laredo 4x4 4.0L — Dead, sold, and rolling again