<p>Bishop Allen Vigneron, the new leader of the Roman Catholic Church in the East Bay, arrives with conservative credentials, friends in the Vatican and a hard act to follow.</p>
<p>Vigneron, an auxiliary bishop in Detroit, was named by Pope John Paul II last week to replace retiring Bishop John Cummins, a popular and relatively liberal prelate who has gently shepherded the Diocese of Oakland for the past 25 years.</p>