Franklin Graham, son of evangelist Billy Graham, believes President Barack Obama defied God by changing his stance on gay marriage.
"President Obama has, in my view, shaken his fist at the same God who created and defined marriage," Franklin Graham said in a statement on the Billy Graham Evangelistic Association website.
The president has proclaimed his Christian faith several times, and before taking office said he thought marriage should only be between one man and one woman.
Over the years, Obama gradually changed his tone on the issue, finally stating in an interview with ABC News Wednesday that his stance had fully "evolved" to support same-sex marriage.
"It grieves me that our president would now affirm same-sex marriage, though I believe it grieves God even more," Graham added.
The well-known evangelist and leader of Samaritan's Purse lives in North Carolina, where voters approved a constitutional amendment to define marriage as only the union between one man and one woman.
"While the move to pass amendments defining marriage is relatively new, the definition of marriage is 8,000 years old and was defined not by man, but by God Himself," Graham said.
He added that there's no need for marriage to be defined by by presidents or polls, governors or the media
"This is a sad day for America. May God help us," Graham concluded.
Franklin Graham has criticized President Obama's policies in the past. Earlier this year, he said Obama "seemed to be more concerned about Muslims than Christians"
The president said he changed his mind on gay marriage after talking with friends and family -- even his two daughters.