He is a religious man by background, a sermonizer by nature, a political evangelist by intent. Yet, at the pulpit of Taylor Memorial United Methodist Church, his voice is tentative.

With the eyes of an unfamiliar black audience on him, John B. Anderson seems more a prisoner than a preacher.

Selecting his words with great care, he praises the pastor. He praises the middle-class congregation, he drops the names of friends and supporters with him. Yet when he reaches the name of Paul Winfield, a black actor who is to endorce him, the candidate mistakenly calls him Paul Warfield, a football player.

He quotes from the old prophets Micah, Amos and Isaiah. His message is of justice, not of political or spiritual redemption. It is not memorable. It takes only minutes to deliver.

Then, John B. Anderson, independent candidate for president, is off to more familiar surroundings -- a press conference across the bay in downtown San Francisco.

Sometimes in these first cool days of September it seems as if Anderson is only comfortable before a television camera or a crowd of college kids.

Under the klieg lights, every campus and every television studio in the nation looks the same. Buffalo, Rochester, Albany, New Brunswick, Los Angeles, Claremont, San Jose.

Anderson has visited these cities on his latest swing trying to reach out to the kids on their campuses and their parents back home in their living rooms with the good news of his independent candidacy.

"We're all independent," he told the crowd of 2,500 at Rutgers University in a booming voice. "We can free ourselves from the tryanny of the established two-party system. We can tell the people of this country that it is possible. That we can win."

He was exhuberant, often eloquent. He drew strength from the League of Women Voter's decision to invite him to appear in the group's presidential debates -- with or without President Carter.

"I think we passed a very significant threshold in the campaign," he said in San Francisco. "It has given me a new hope, a new confidence, a new belief that his campaign is a plausible one. It is something doable. We are not simply on a hapless, suicidal adventure."

Moral outrage has always been Anderson's most powerful emotion. He controlled it effectively, holding back his criticism of Carter for refusing to debate when Anderson was invited.

Yet Anderson is a complex and stubborn man. And he appeared to be undergoing a painful inner struggle over his place in the campaign last week, a delicate balancing act over how to emerge as a serious contender.

At several stops, he returned to the anti-politician theme that first brought him to national attention during last winter's Republican primaries.

"Telling you the truth about the real issues is much more important than just winning in 1980," he said in Redondo Beach, Calif. "We're out here to shake up the system and it needs to be shaken up badly."

But two days later in San Francisco, he was retreating on that statement, struggling to explain how, if his candidacy resulted in Republican nominee Ronald Reagan beating Carter, the system would be shaken up.

"If Reagan should be elected, the Kennedy wing of the Democratic Party would be in ascendancy," he said at one point. ". . . I think that would be a healthy thing."

Talk of realigning the power structure of the Democratic Party and of not caring about winning the Nov. 4 election, however, was strange coming from a lifelong Republican, who is asking people to give their time and money to get him elected.

Anderson's traveling press secretary Tim Mathews, attributed this to "a paradox in the Anderson campaign."

"It's only by taking his eye off the presidency that he can win," said Mathews. "The minute his vision goes toward winning, he immediately loses strength. His best ground is telling people the truth: that the country is in trouble and there are solutions, but they hurt."

For most of the summer, Anderson rejected this theory, acting more and more like a conventional political candidate. His standing dropped steadily in the polls. By the end of August his campaign was severely strapped for money and in internal disarray. "The canoe was about ready to go over the waterfall," said one aide.

Since then, Anderson has had a run of good luck. He has found a vice presidential running mate, released a party platform, recieved a federal Election Commission ruling that makes him eligible for retroactive public campaign subsidies, been endorsed by New York's Liberal Party and been invited to participate in the presidential debates.

He has also succeeded for the first time in getting Carter to mention him. A few hours after the president last week said he regarded Anderson "primarily as a creation of the press," the Illinois congressman jokingly told reporters, "I feel very humble. I'm standing before my creators."

Everyone laughed. But there was a strong element of truth to the president's remark.Throughout the year, Anderson has benefited from a favorable press. But his campaign remains underfinanced, largely amaetur effort devoid of support from traditional politicians.

It is essentially a media campaign with no money to buy television commercials, and not enough workers to put together more than a couple of rallies a week.

So Anderson resorts to hopping around the country holding press conferences, giving television interviews and visiting college campuses, where it is easy to draw a crowd. The first three days of this week, for example, he scheduled four press conferences, one college rally and only one other noncollege speech -- before a women's group in Portland Ore.

Even more troublesome are the constant reminders that much of the public still regards him as nothing other than a "spoiler," someone who can hurt Carter, and to a lesser extent Reagan, but can't himself win.

Anderson has come up with a new answer to that criticism. "a vote for Cater is a vote for Carter. A vote for Reagan is a vote for Reagan. And a vote for John Anderson is a vote for John Anderson," he said on one San Francisco talk show.

"Any time we decide this is just another sporting contest and put our money on the horse that's going to come home first rather than the horse that's going to show, think we've ridiculed the importance of the whole election."

But skeptics remain. After a well-attended rally at San Jose State University, Diane Soloman, a senior said: "He sounds good. I like his platform. And it's great to have him come to my school. I voted for him in the primary. But if it looks like he isn't going to win, I don't want Ronald Reagan to be president."