(CNN) -- Prominent liberal groups and gay rights proponents criticized President-elect Barack Obama Wednesday for choosing evangelical pastor Rick Warren to deliver the invocation at the presidential inauguration next month. Warren, one of the most influential religious leaders in the nation, has championed issues such as a reduction of global poverty, human rights abuses and the AIDS epidemic. But the founder of the Saddleback Church in Lake Forest, California, has also adhered to socially conservative stances -- including his opposition to gay marriage and abortion rights that puts him at odds with many in the Democratic Party, especially the party's...