2008 Jeep Wrangler won't start but lights come on

Are you saying the engine will not crank at all? Or it cranks but doesn't start? If it is no crank, then check the battery cables and connections for possible corrosion and fit. Then, even though you say it's "not a battery issue", the battery itself will first need to be tested to see if it has the ability to sustain a load from the starter. Lights on but no crank could still be a battery with the inability to start the engine. If the battery passes voltage and load testing, then further testing in the starting system should be performed, including testing the starter motor. This is merely a start, as there are several possible causes, but hands on inspection by an experienced technician would definitely get to the bottom of your concern.