The Post's editorial ''The Right Way on Contra Aid'' {Dec. 20} urging Congress to keep funding the contras demonstrates how little has been learned from the futile seven-year undeclared war against Nicaragua and the contents of the recent Iran-contra affair report.

The duties for the U.S. government that The Post mapped out are grossly misplaced. Why not call for a return to good old-fashioned diplomatic energy rather than ''applying the pressure of bridge aid'' in the hope that the contras will somehow produce an outcome to our liking?

And doesn't it seem hypocritical to call for Mikhail Gorbachev to end all military aid to the Sandinistas when the Reagan administration shows no interest in ending the long love affair with the contras and continues to militarize hapless Honduras? Moreover, it is sanctimonious to assert that we have to do what we can ''to hold the Sandinistas to their pledges of a political opening'' when it should be clear by now that the contras are not the harbingers of peace and democracy in Central America.

It is a sad chapter in our relations with Latin America to see how decisions based on such pervasive dishonesty, intelligence abuses and disdain for law can still remain legitimate policy. A recent series of articles in the Philadelphia Inquirer on the contra war clearly indicate that the contras are ''reluctant warriors'' fighting a ''futile war.'' It's time to stop romancing the contras with the promise of continued support. The right way on contra aid is to end it altogether. DAVID W. DENT Reisterstown, Md.