RONALD REAGAN and Mikhail Gorbachev can talk about a dozen subjects and get along pretty well. There is one that is particularly sensitive for Mr. Gorbachev, however, and it is the one that, when raised, provokes his most irritated response. It is the issue of human rights in the Soviet Union - the rights of innocent Soviet citizens to be free from imprisonment, to be free to travel, to criticize their government, to be free to pursue the religion of their choice.
Gorbachev's view is that this is an internal matter. Neither the United States, nor any other foreign country, he contends, has the right to tell the Soviet government how to treat its citizens.
There are some people outside the USSR who echo this view, namely, that the US has enough to correct within its own society before it meddles in the internal affairs of another.
But all the evidence is that pressure from the outside world has played a significant role in some of the liberalization that has taken place in the USSR. It is pressure that President Reagan should maintain during the coming Moscow summit.
Clearly, there has been improvement under Gorbachev's rule. Some political prisoners have been freed. Some Jewish dissidents have been permitted to leave the USSR. In the area of religion, Gorbachev has met with Russian Orthodox leaders, and has permitted the renovation of the Russian Orthodox Danilov Monastery. A kosher restaurant has opened in Moscow, religious literature is more freely available, and the regime has announced it will permit celebration of the millennium of Kievan Russian Christianity.
But as the freed Jewish dissident Natan Sharansky points out in a column in the New York Times, only the ``unforgivably naive'' can believe the Soviet leaders do anything benevolent because they have seen the error of their ways. When they make progressive changes, it is for pragmatic reasons.
Gorbachev, Mr. Sharansky contends, is a supreme realist. He knows the Soviet economy is disastrously backward. He thinks the decay will be irreversible unless the West comes to his rescue. To get Western cooperation, he has to improve the USSR's image.
It is, he says, a ``balancing act between the minimum required to satisfy Western sensibilities and the maximum the Soviet system can bear. Had Gorbachev felt the Soviet economy could be revitalized without liberalization, there would have been none.''
Religion has benefited from the loosening-up process. But a new study by the Washington-based Puebla Institute finds that ordinary Soviet citizens of all faiths continue to be denied the right to worship and practice their religions without state interference.
The institute is a nongovernmental lay Roman Catholic human rights group, focusing on freedom of religion around the world. The report lists religions that are banned in the USSR but says that even in the case of ``legal'' religions, worship is prohibited except in state-approved buildings by state-approved congregations. Organized religious instruction and Hebrew training for young people, and religious and Bible discussion groups for adults, remain prohibited.
More than 200 religious believers continue serving sentences for religious reasons. The state, says the Puebla Institute report, routinely interferes in the designation of religious leaders and in church administration. The longest-term religious prisoner, the Russian Orthodox Vasily Shipilov, was arrested in 1939 for studying and preaching the Bible and, with the exception of one year of freedom, has been in labor camps or mental hospitals for 48 years.
All these are good reasons that Mr. Reagan should continue pressing Mr. Gorbachev on human rights.