God tells Joan she’s only just begun on the second-season finale of “Joan of Arcadia” (7 p.m., CBS). The Almighty informs our plucky high schooler that her first two years have been a kind of spiritual boot camp, mere training for the battle to come with a mysterious man with an unholy agenda.

But will Joan get her chance to enter battle? God may be on her side, but is Viacom? Tonight’s real cliffhanger involves the fate of the show itself and its uncertain prospects for a third season as the networks prepare to announce their new schedules.

“Joan” had a strong first year, but saw its ratings weaken in its sophomore outing, despite much talk of the need for more “faith-based” programming. “Joan” may be prepared to battle the forces of darkness, but she might not be able to stem the flight of Friday-night viewers. “Joan” seems to be following the ratings trend of NBC’s “Providence,” another family-friendly, Friday-night, supernatural drama that started strong and petered out after a couple of seasons.

Tonight’s other highlights

• A rising political star (Ralph Fiennes) falls for a hotel domestic (Jennifer Lopez) in the 2002 Cinderella tale “Maid in Manhattan” (7 p.m., Fox).
• The crew meet their evil twins in a dark parallel universe on “Star Trek: Enterprise” (7 p.m., UPN).
• Harm and Vukovic come to the defense of a seaman accused of murder on “JAG” (8 p.m., CBS).
• A traffic delay turns deadly on “Third Watch” (8 p.m., NBC).
• Terrorists cobble together a “dirty bomb” on “Numb3rs” (9 p.m., CBS).

Note: Listings may vary based on coverage of local baseball games.