"This is heaven," Redskins owner Jack Kent Cooke said, surveying the wreckage of the Detroit Lions, beaten every which way at RFK Stadium yesterday, the damage being 31-7 before mercy obtained. Saying the same thing another way, the team president and distinguished barrister Edward Bennett Williams said, "We're kicking the gol-durn heck out of them." Not in those exact words.

For the first time in a decade, the Redskins have won a playoff game in the National Football League. George Allen and Richard Nixon were in town back then, it was so long ago, and in those 1972 playoffs the Redskins didn't lose until the Super Bowl, there falling to the perfect-season Miami Dolphins. Three times since, the Redskins have lost in the playoffs' first round.

Not this time. Not with Joe Theismann throwing superbly. Not with little Alvin Garrett catching three touchdown passes (he'd caught only one of those in almost three pro seasons). Not with the tractor-trailer John Riggins rolling over bodies for 119 yards. And certainly not with the Redskins' defensive unit intercepting two passes, recovering three fumbles and turning Detroit quarterback Eric Hipple on his ear four times.

The sick rose from bed, Saturday workers called in lame excuses (never, probably, have so many Washingtonians had car trouble simultaneously) and the full complement of 55,045 sophisticates (no no-shows, none) turned RFK Stadium into such a screaming funhouse that defensive end Dexter Manley said, "Y'know, this town is wholly crazy about us."

Bedsheet banners at RFK yesterday: "D. Butz, Secretary of Defense" . . . "Moseley for President" . . . "Go Piglet, #7." That last is a cryptic reference to Theismann, who helped out the hallowed "Hogs" of the offensive line by throwing a block last month. All about RFK these days there is a sense of--dare it be said?--destiny crooking a finger at the Redskins, because suddenly where so much has gone wrong in a decade now everything is going right.

How else explain the exquisite rightness of Mark Moseley setting an all-time NFL record of 21 straight field goals with a last-gasp kick to beat the New York Giants, 15-14, to win the game that put the Redskins into the playoffs? Or how explain that, with star receiver Art Monk on crutches, the obscure Alvin Garrett comes in to make three touchdown catches?

"The best thing we have is a belief in ourselves," said free safety Mark Murphy, which is exactly what destiny in sports is all about. Luck is the residue of design, Branch Rickey said. The more talent you have, the luckier you get. "Our defense now has succeeded often enough this year that, when it comes down to it, we expect to stop the other team."

Barely had the 55,045 folks settled into their seats yesterday when Detroit began an ominous march downfield. This against the Redskins defense that in three previous games had not given more than 200 yards to anyone. But in only four plays, the Lions were on the Redskins 21-yard line.

Luck? Destiny? Great players well coached? A little of everything went into the next play, when Redskins cornerback Jeris White intercepted Hipple's little pass and sprinted 77 yards the other way for a touchdown that established the rhythm at which this game would be played.

Every Detroit threat would be stopped by a Detroit error which the Redskins would turn into offensive capital. White later said he only tried to knock the ball down, not intercept it. But it popped straight up and danced before his eyes, as if on some heavenly string. "It stayed in place long enough for me to grab it," White said.

After that, it was Garrett's day. He caught six passes, as many as he had caught in his entire professional life, and took part in a five-man, gather-in-a-circle, sky-high, high-five celebration in the end zone after his third touchdown. The "Fun Bunch," as they call themselves, rocked on their heels first, swung their arms in careful choreography and then leaped high to slap hands. Film at 11.

So perfect was this day--on a January day so Indian summery it moved the Redskinettes to wear their bare midriff outfits, the Redskins were as dominant a team as this town has seen in a while--so perfect was it that Jack Kent Cooke asked his publicity office to put out a press release about perfection.

The Redskins sold every seat for the 120th consecutive time, and for the first time this season every seat was filled. No other team had no no-shows in this half-season of the players' strike. "Perfection sits not only on the field at RFK Stadium," the release said.