Billy Connolly's first comic screen role sees the Scottish comedian playing Steve Myers, an Australia–based fisherman whose boat is sunk by lightning. Although his policy is supposedly comprehensive, the small print reveals that the insurance company is not liable for damages caused by Acts of God. Irate, he decides to sue God for damages. Is he a hero or a heretic? It's a whimsical premise, but in unpacking its consequences director Mark Joffe offers a valid comment on the inter–relations of a very unholy trinity — organised religion, law, and commerce.

It's no spoiler to reveal that Myers wins the case and that at no time does God appear, like a Terry Gilliam animation, to smite him down. The film follows a fairly predictable narrative trajectory — man meets woman, obstacles are overcome, lovers sail off (literally) into the sunset.

Ann Redmond (Judy Davies) is a disilllusioned journalist searching for meaning whom Myers collapses onto while drunk in a restaurant. This coincidence, one of many in the film, leads to an effective legal partnership.

The reliance on serendipity makes the film less sermonising; a more open–ended proposition. But instead of leaving viewers stranded between the devil of certainty and the deep blue sea of doubt, Joffe offers true believers a few key get–out subclauses: first, there is the mechanical breakdown that leaves Myers aboard his motorboat as his fishing craft explodes, then his fortuitous encounter with Redmond in the restaurant. Later, Myers is desolate as the case flounders, and stares at a starry sky asking for a sign. He turns his back as a shooting star arcs across the heavens. And when he visits a church, for reasons never clarified, a janitor advises Myers to "drop his case". Upon repetition, it transpires he has actually said "You've dropped your case", meaning Myers' forgotten satchel. Then there's the pathetic fallacy of bush fires and pestilential winds against which the court case plays out. (The film, for all its atheistic overtures, is unafraid to borrow Biblical structures and myths wholesale.)

But this ambiguity of intent strengthens the film, so when Myers boards a bus run by the Eden company after confronting his lawyer brother with evidence of the latter's treachery in siding with the prosecution, we indulge it.

Maybe this is because Myers critiques the institutions of religion and commerce succinctly — in court he derides the church for its hypocrisy, noting that its assets are worth more than the entire third world's debt. This duality is illustrated deftly as the church elders who have been called in to defend God in lieu of the absent Almighty try to conspire a way to win the case without showing that God is a fiction. And this during a moment's meditation during a poverty–relief conference.

For all this, the church doesn't come out of it too badly. Vincent Ball's courtroom defence of the mystery and majesty of religious faith is poetic and almost profound, and Myers seems, for a moment, swayed. Linal Haft as the Rabbi gets all the best one–liners, although he is a parody of Jewish black humour, driven by financial imperatives as much as the insurance companies. But when Myers reminds the court that most major world religions own shares in insurance firms, the film is given a brief dramatic charge — welcome in a late–summer feelgood rom–com.

It's a clever–ish conceit — the anonymous, pitiless corporation is paralleled by a globalised unforgiving, uncommunicative god. The inhumanity of two systems that offer hope to the insecure — faith and insurance — is stripped bare. The massive profits of the multinational are weighed against the individual losses of the claimants who form the class action that Myers launches. Religious faith is, after all, the ultimate insurance policy: our reason and our logic is the premium we pay in the hope of something which never comes — eternal life.

But Joffe seems to quail in the face of outright heresy, and, in a crisis of faith, dwells on Myers' relationships with his ex–wife, his brother and his 12–year–old daughter, instead of the philosophical riddle at the film's heart. And while Connolly is on fine, irate, gutter–mouthed form, the slapstick elements serving as comic relief can be a little clumsy at times.

Cynics will be disappointed to hear that during filming, screenwriter Don Watson's house was struck by lightning, destroying almost all of his electrical goods, but his insurance company agreed to pay out. An extra balanced the books when a branch fell on his car. The insurance company claimed it was an Act of God. n

The Man Who Sued God (cert 15) is released 22 August.