ALMOST 1000 angry students gathered in front of Memorial Church on a bitterly cold winter evening three years ago. They were protesting then-President Jimmy Carter's recent reinstatement of draft registration and the bankrupt, militaristic foreign policy it reflected.

Campus activists are sponsoring another anti-registration rally tonight, and the need for high student attendance seems even greater than it was in January 1980.

President Reagan, who pledged during his campaign that he would scrap registration, has not only broken that promise, but has put more teeth into the provision. The Justice Department this summer began indicting non-registrants, and Benjamin H. Sasway, convicted in August, will this afternoon become the first American sentenced for such a "crime" since the Vietnam War.

Congress has also been on the offensive, recently approving legislation that would link an individual's right to receive any type of federal assistance--including student aid to registration compliance.

But as the program itself has become stronger, Its justification and its utility have been exposed as quite weak. Out of anger and apathy, more than 500,000 young men have so far avoided the law. Recent indictments may lower that figure, but congressional studies show that it would be almost impossible--not to mention grossly wasteful--to rope in a significant portion of the violators. To continue with the current half-hearted, selective prosecution policy would be unjust.

The new student aid provisions will, at best, create headaches for financial aid officials, and, at worst, foster student-administration divisions reminiscent of the late '60s.

The benefits accrued for these significant costs would most likely be no more than seven days of mobilization time in the event of a war--a saving which many experts agree is meaningless. President Reagan's motivation, then, for persisting with such a program is clearly to preserve it as a symbol for a hard-lined, bellicose approach to international relations.

At a time when our leaders think they can slip this past an unwary country, students must demonstrate that they actually care--and strongly oppose--this tack. Tonight, at 7, on the steps of Memorial Church we have that opportunity.