[ No headline ]

There are three separate and distinct elements in the mutual fear (hence hostility) in the US-Soviet relationship which have caused the massing by these two superpowers of the mutual ability to destroy each other and perhaps the human race.

One of these elements is the fact that they are the only two superpowers in the world and the only ones economically capable of amassing rival arsenals of more than 8,000 nuclear warheads aimable at each other. The mere fact that there are no others of similar power makes each especially sensitive about the other.

The sensitivity is enhanced by conflicting ideologies. In the Soviet ideology of Marxism, the system prevailing in the United States and among its allies and associates is sinful. To any Marxist, capitalism spells exploitation, hence should ultimately be wiped out in favor of a moral, i.e., Marxist, system.

To practitioners of Western-style market economy, the Marxist system is sinful. It is usually referred to in such pejorative phrases as ''godless communism.'' To Western ears, it spells destruction of Western cultural values. Therefore, it should ultimately be wiped out in favor of a moral, i.e., capitalist, system.

The third element behind the mutual fear is the mutual reaching for physical elements of security. This not only means rivalry in stockpiling arsenals of nuclear weapons; it also means rivalry in attracting friends, associates, and clients, particularly those whose association can bring with it military advantages such as air and sea bases.

The combination of the three factors merges into today's world, in which the US seizes the island of Grenada, partly to make sure that its new airfield under construction does not become a military asset to Cuba, and conceivably someday to the Soviets. And in this same world of today the Soviets deny political and economic independence to their neighbors in Eastern and Central Europe lest Poland, East Germany, Czechoslovakia, Hungary, and Romania backslide into Western capitalist ways and Western associations.

This rivalry in securing new military assets and clinging to old ones feeds on itself. Every time the Soviets deploy another weapon, this becomes a new ''threat'' to the US which must be balanced by deployment of another Western weapon. And every time some American trade union makes a contribution to Solidarity in Poland, this becomes in Soviet eyes a ''threat'' to the security of the Soviet Union itself which must be countered by help to rebels in El Salvador.

The most intractable and difficult to dissolve of these three elements which lie behind the fear, the rivalry, and the hostility is the ideological. History teaches many a lesson about both the tenacity of ideological rivalries and the damage they can cause.

For example, this week in Rome the head of the Roman Catholic communion, Pope John Paul II, entered and preached a sermon inside a church of the Evangelical-Lutheran communion. Martin Luther, the founder of the Lutheran Church and indeed a prime source of all Protestant religious groups, was excommunicated by the Catholic Church in the year 1521. It has taken 462 years for the common bond of Christianity to bring a Pope into a Lutheran church. It has not happened before this week.

During the intervening 462 years, many a war has been fought between Roman Catholics and Protestants over their religious differences. The ''Thirty Years' War'' in Germany and the Battle of the Armada between Spain and England are the two best known. Hundreds of thousands of human lives were spent in those and the other religious wars of the 16th and 17th centuries.

Scars remain to this day. Not until 1960 was it possible for a Roman Catholic to become president of the US. John F. Kennedy's presidential predecessors were Protestants, and most were members of the Masonic order.

The rivalries of communism vs. capitalism are as emotional and as ideological as ever were the rivalries between Roman Catholics and Protestants. To Ronald Reagan, the Soviet Union is inherently ''evil.'' He calls it ''evil,'' and so does the evangelical Protestant preacher, the Rev. Jerry Falwell. Emotion is heard vibrating in the denunciations of communism by both of them, as it does in the voice of true believing Marxists when denouncing the alleged sins of capitalism.

The chasm between Moscow and Washington is deep and full of angry waters. It is probably deeper right now than at any time since Stalin launched the ''cold war'' in 1946 and Winston Churchill identified the condition in his ''Iron Curtain'' speech at Fulton. But it has been bridged, and it could be bridged again in the face of the present nuclear threat if and when the time may be more suitable than right now.

To be continued on Tuesday