1989 Jeep Wrangler Battery fully charged; engine won't turn

No engine turnover. If you meant it cranks over and will not start do below to determine if its fuel or spark issue

Disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, distributor pick-up coil, ignition control module, cam and crank sensors- Note: If it doesn't apply disregard it

Load test the battery if okay clean battery posts/cables and tightened properly don't work start checking the starter, starter relay, clutch switch and ignition switch