Theatre/ The Devil has all the best tunes/ The Boat Plays/The Gate: The Man of Mode/ Royal Court

At this time of year, you'd have thought shepherds would enjoy a higher profile and better press than normal. But to judge from The Boat Plays at the Gate, the season of goodwill, even back in the early 16th century, tends to expose anyone associ ated with a crook and a flock to an undue degree of satirical stick. The second of these rare and now handsomely revived plays by the Portuguese writer Gil Vincente takes place on Christmas Eve and shows the Devil and an Angel competing for the souls of a procession of the recently departed.

Which is where the Shepherd, swathed in fleece, puts in a clumping appearance.

"If you are looking for a stable, mate / You're about 15 centuries too late," jeers the Devil in David Johnston's canny, glintingly comic translation (that larky wordplay on "stable-mate" typical of its manner).

Disabusing the rustic of the idea that a life of relentless hard work is any excuse for not having concentrated on matters godly, the Devil also subjects his peasant diction to a brisk going-over, snapping, at one point, that "The correct term is `hark' / Especially at Christmas to shepherds in the dark".

But though a third of the piece is set on Christmas Eve, it would be a mistake to think of this production, powerfully directed by David Farr, as an alternative Yuletide show. What matters more than the season is where these plays happen (on the border between damnation and salvation) and the historical period in which they were written (the gold-rush, colonialist fever of the early 16th century).

Imagined as a performance before Queen Isabella of Portugal and her court, the plays amount to a political as well as a theological indictment, reserving their most acrid indignation for those corrupted by power in both church and state.

Angela Davies's superb design transforms the auditorium into a ship bound for hell with the audience as its passengers. At the end of each row, pew-like doors shut you in and form the side of the vessel. Representative types (a Procuress, say, with a bl o ody bag strapped round her waist) file on to the quay in succession and contend with Tony Curran's playfully scathing, charred-winged Devil in terms that are tragicomically trapped in the obstinate benightedness that led these people astray in life.

I found the theology a trifle confusing. On the one hand, Vincente seems to be making an increasingly defiant, Miltonic case. "I didn't fall; I was pushed," claims the Devil; and when the masked potentates arrive in the last play (in a glittering procession like some slowed-down, Kabuki-fied re-run of the clerical fashion show in Fellini's Roma), there's no doubt that Authority is getting it in the gem-encrusted balls. But then, in the last moments of the piece, they strip themselves of their finery andare received into heaven to the strains of Palestrina. That's the snag about the last-minute repentance gambit. Manage one, and you are quids in, no matter though your career has been round-the-clock cruelty and corruption. Fail at the finishing post,and it's hell-fire forever, despite your relatively modest portfolio of mortal sins.

One (virtually) deathbed convert was the Restoration rake Rochester, and certainly heaven will be an infernally dull place if it does not contain a few more like him. He's the subject now of the two works which Out Of Joint have brought to the Royal Court: a new play, The Libertine, by Stephen Jeffreys (reviewed here a week ago) and George Etherege's 1676 work The Man of Mode, where the Earl crops up in the fictionalised form of the womaniser Dorimant. Perhaps because The Libertine is designed to blow the gaff on certain distortions and evasions in Restoration comedy, Max Stafford-Clark's entertaining production of The Man of Mode uncharacteristically downplays some of the unlovely realities already there in the Etherege.

But what a rich, thought-provoking pairing these two plays make, and not just in the contrast they afford between the disease-immune Dorimant and the debauched wreck that is Rochester in The Libertine.

Of greater fascination is the disparity between their respective spouses. In the witty, resourceful heiress, Harriet, Dorimant seems to have met his match in both senses. The Libertine, though, winds the clock forward and in the humiliated yet dignified figure of Rochester's wife, Elizabeth, shows you how life could turn out for an intelligent woman married to someone at once incorrigibly captivating and amoral. Both women are admirably played by Amanda Drew.

Gate Theatre: 071-229 0706 Royal Court: 071-730 1745