The scandal-tainted pastor of a vast Atlanta megachurch was cheered to the rafters by a 10,000-strong congregation today as he took to the pulpit with a vow to fight accusations that he took sexual advantage of four teenage men in his flock.

Bishop Eddie Long, a vigorous advocate of sexual abstinence who once described homosexuality as a "spiritual abortion", leads one of America's largest and most powerful black churches, the New Birth Missionary Baptist Church in Georgia.

Renowned for his expensive lifestyle and celebrity connections, Long this week faced lawsuits claiming that he lured young men into sexual relationships with cash, jewellery and electronics at a youth academy billed as a "rite of passage" for males. Mobile phone photos have surfaced, allegedly sent by Long to the young men, which depict the 57-year-old pastor posing in front of a bathroom mirror in tight-fitting muscle shirts and cycling shorts.

In his first public appearance since the civil suits were filed, Long compared his situation to David's biblical battle with the giant Goliath at the Sunday service of his $50m (£31.6m) cathedral. But he avoided any direct admission or denial of wrong-doing.

"I have never in my life portrayed myself as a perfect man. But I am not the man that's being portrayed on television," Long declared, as he was interrupted by a thunderous standing ovation. "That's not me. That is not me."

Dressed in a Star Trek-style high-necked cream suit with his wife alongside him, Long said nothing about the actual allegations but talked in general terms about facing up to challenges: "The righteous face painful situations with a determined expectancy."

In a speech broadcast live on US television, he made clear he would battle the accusations, telling the crowd: "This thing I'm going to fight."

To further applause, he said: "I want you to know one other thing. I feel like David against Goliath. But I got five rocks, and I haven't thrown one yet."

The lurid accusations against Long have sent shockwaves through the devout southern community of Christians and have drawn comparisons with Ted Haggard, the charismatic leader of a prominent evangelical church in Colorado who was obliged to quit in 2006 when a male prostitute came forward, claiming to have had amphetamine-fuelled sex sessions with him.

Long's church is much bigger than Haggard's former ministry, having grown from 300 to 25,000 members since 1987, with satellite churches as far afield as California. New Birth's cathedral in Lithonia, near Atlanta, hosted the funeral in 2006 of Martin Luther King's widow, Coretta Scott King, which was attended by presidents George W Bush, Jimmy Carter and Bill Clinton.

The men suing the bishop say that he took advantage of them when they were aged 17 and 18 – above the legal age of consent but in a breach of pastoral trust. One of the litigants accuses Long of abusing him after giving him a sleeping pill during a trip to Kenya.

Regardless of whether the accusations are true, the case has renewed a debate about checks on the power of leaders of America's independent churches, which can be enormously influential in local communities.

"The more powerful a Christian leader becomes, the fewer restraints that other people can put on them," the Rev HB London, vice-president of ministry outreach for Focus on the Family, told the Associated Press. "Some of these men and women become so powerful that no one can tell them 'no'."

Long has frequently been put on the defensive about his wealthy lifestyle – he drives a $350,000 Bentley, lives in a $1.4m nine-bedroom home and was paid $3m between 1997 and 2000 by his non-profit religious charity.

At a brief press conference after 's service, Long refused to take questions, citing legal advice, and simply said he wanted the allegations to be dealt with by a "court of law" rather than by public opinion. His lawyers have explained Long's bathroom photography by characterising him as somebody keen to spread a positive message about weight-lifting and good health.