Is it unsafe to drive a jeep with bad ball joints?

A bad ball joint isn't safe any way you look at it. Some major damage can happen if the wheel becomes dislodged from the chassis. The major component holding the wheels on are the ball joints, upper and lower, which hold the spindle that houses the axle. The spindle holds the wheel bearing, tie rod, brakes, wheel etc. You can lift the vehicle up by the front and check the wheel for play, up and down. There shouldn't be much, if any play. If there is alot of play then you shouldn't drive it much till it get's fixed. That's my opinion. Good luck.