Despite some ugly talk that his ordination might be revoked, thus making him one of the few unfrocked German shepherds of metropolitan Washington, the Rev. Rex, the clerical dog, has a green light. It is entirely possible he may become an archbishop.

At first, the American Fellowship Church of Monterey, Calif., felt it had been abused when the owner of the dog applied for him to become an ordained minister of that church.

"It was meant as a joke," a spokesman for the church said, when informed by a reporter that Rex was a dog, "but it is not very funny."

The American Fellowship Church is one of several that ordain their priests by mail. If you are rich, you are invited to send them $3, but if you are poor, they will ordain you free.

As the example of Rex well illustrates, there are not a great many requirements for ordination.

Because religion, for some reason, excites passions among many citizens, possibly in inverse ratio to the seriousness with which religious precepts are adhered to in daily life, some opposition has been informally registered to the ordination of Rex and other dogs. (Reporters have been informed of additional dogs that have become priests by mail).

Some have suggested it ought to be against the law for dogs to be made priests, while others believe it is already against the law. It is not entirely clear whether a German shepherd, or for that matter a great hound, even, could conduct a legal marriage ceremony, but conservative attorneys tend to recommend their clients not rely on the validity of such rites. Funerals are something else, and in the present state of liturgies there is a body of opinion that a dog could do it about as well as the new Book of Common Prayer.

So much for the background. The first question, the legality of ordaining humans by mail order, without any special qualifications or course of study, has been answered authoritatively by a federal court (U.S. District Court for the Eastern District of California in Universal Life Church Inc. vs. United States, March 1, 1974).

Such ordinations are perfectly legal. Furthermore, mail-order churches are not subject to income taxes any more than the better-known churches are. The same Constitution that allows Presbyterians to run loose, as you might say, applies to the mail-order churches. The court does not endorse any church or rebuke any church, as long as it can show it is concerned (at least to some extent) with religion and is not merely a subterfuge for making money.

The court examined claims of the income-tax arm of the government that a mail-order church was not really a church and was not entitled, therefore, to the usual tax exemptions of the Episcopalians, Baptists, Catholics, etc.

The court found no reason to deny the protection given those churches to the mail-order church. It is not the function of the court to evaluate the content of any church's dogma, if it is not in open violation of American law.

In the case of the Universal Life Church Inc., the court held that whether or not anybody approves of its somewhat informal way of ordaining anybody who applies, it is a valid church for purposes of taxation. The court told the income-tax people off, and made the government refund any unjust taxes that had been collected from the church.

This federal decision has not been overruled and appears to be the law of the land, and appears to apply to Rex's church, the American Fellowship Church, as well as to the Universal Life Church.

So there is no question the church is a legal church. The question remains whether a dog's ordination is valid -- nobody says it is regular -- since it was granted without knowledge that Rex is a dog. A very nice dog, admittedly.

Here we hit thorns. Churches established far longer than the American Fellowship Church (not even a generation old) are still wrangling whether the clergy of various churches are really kosher.

In an age of ecumenism, these arguments are not loudly raised nowadays, but they are still there. What's a valid baptism? Can any Christian baptize or must it be an ordained clergyman, and if so, can it be any clergyman? Can Rex do it?

Could a cat -- even if one accepts dogs of the better breeds -- perform the duties of a clergyman? And if a cat, how about a white mouse? A possum?

Could an oak or a rose be ordained? How about an ashtray? Would it have to be alive? What about algae?

Theology has always been a technical matter. Things that at first seem obvious and simple are by no means so simple. Things have ramifications.

The Rev. Ted Swenson, titular head of the American Fellowship Church, has not tried to duck or pussyfoot the question but has doggedly attacked it head-on in a pastoral letter to the newly ordained dog. Mr. Swenson has shared this letter with The Washington Post, which in the interest of clarifying this somewhat obscure issue to some extent, herewith prints it:

Dear Rev. Rex:

No doubt you have heard about reports in various newspapers saying that our Church plans to withdraw your ordination.

To tell the truth, we had planned to do that.

That is, until a local TV station mistakenly quoted me as saying dogs do not have souls.

Reverend Rex, that made me mad but it opened my eyes. Dogs and other animals do have souls. When I peer into the eyes of my dogs I know that is true.

(EDITORIAL NOTE: Whether dogs have souls is a vexed question. A famous mystic was once offered direct entrance to Paradise but refused. "Not without my dog," he stated. This raised and still raises the profound question whether a moral man or indeed even a saint is correct to accept celestial bliss as reward for his own virtue, leaving the devil, as it were, to take the hindmost who have lesser reputations for righteousness.)

To continue with the pastoral letter to Rex:

Reverend Rex, before I founded our Church, I was dean of students at the University of California at San Francisco. While I held that position I related to people with all kinds of impressive degrees and credentials. I had lunches at the Bohemian Club and the Union Pacific Club.

(EDITORIAL NOTE: These are clubs that even Anglicans might dine at, and the Rev. Mr. Swenson thus indicates he is not some sort of barbarian but is someone that anyone might have met at some reputable place.)

To continue his letter to Rex:

But, Reverend Rex, I don't think any of those people had more spiritual insight than many of the fine folks we have ordained through the mail. John Lennon was a minister in our Mother Earth Church and no one seemed to question his credentials. Nor need anyone question the credentials of all the regular folks who have been ordained in our Church and found themselves growing and developing spiritually as a result.

(EDITORIAL NOTE: Here Mr. Swenson seems to be alluding to the priesthood of all believers, or else, indirectly, to the awkward fact that the Apostles were men of deplorable worldly status, etc., and not likely to have been invited to the Bohemian Club, etc.)

He continues, to Rev. Rex:

Our country has freedom of religion and this freedom is protected by the Constitution. I think God has spoken to me through you.

(EDITORIAL NOTE: It is well known that God once spoke through Baalam's jackass and by other unusual means and, as a great dean once observed, it is hardly doubted that any noise may be music if God sets his hand to the instrument.)

The letter to the dog continues:

You and other animals can teach us humans a lot about spirituality and if we can learn from you, then you can be ministers.

(EDITORIAL NOTE: One of the most beautiful of Santayana's passages deals with the essence of angels, which is to say as indeed the Greek imports messengers. There are dark angels, bearing messages we do not relish. There are bright angels, too, of smiling mien and amply graced. Mr. Swenson merely appends a wagging tail here.)

He continues:

Our Church, therefore, not only stands behind your ordination but invites any other animals who wish to be ordained to step forward. We humans may have unique characteristics but in the realm of the spirit we are not alone.

He concludes with the reminder to Rex that:

You can attribute to our achieving that spiritual growth. Please stay with us, and forgive me for thinking of withdrawing your ordination. May God bless you.

The letter is signed Ted Swenson, Rev. Ted Swenson.

The church in general has tended to grow not all at once but by degrees. Doctrines have altered within the fiction of unalterability. Sometimes ancient formularies have been retained, but so heavily infused with new meanings or new feelings as to be scarcely recognizable by ancient men. Commonly these changes are accepted with good grace by sweaty laymen, provided the changes are not too sudden or too clear-cut.

Mr. Swenson, it is to be noticed, while inviting "any other animals" to "step forward," does not specifically mention any except dogs. Whether people would accept cats, at this stage of current spiritual development, or possums or bluejays or tigers, he does not specifically consider, probably wisely, and doubtless relying on a high performance by clerical dogs to ease the way for the others.