2003 Dodge Caravan Engine won't start

I turn the key in the ignition switch and all I can hear is the starter relay in the fuse box making a single click noise but I don't hear the starter turning or any other noise. I discarted a possible battery problem because everything inside the van works just fine; The radio, the lights, the horn, etc. And it's also holding the charge. Is very strange because the day before my vehicle was working fine and it was fully operational. What could be the cause of this problem?