Even though Pastor Rick Warren has joined the advisory board of U.S. Republican presidential candidate Marco Rubio, the Saddleback Church pastor is stressing that he is not endorsing Rubio.

According to The Christian Examiner, several prominent evangelicals including Warren have joined Rubio's Religious Liberty advisory board. However, "The Purpose Driven Life" author does not want people to misconstrue his involvement there as an endorsement.

"It is public knowledge that I never have endorsed a political candidate and never intend to," said Warren. "It is not my job as a pastor to endorse candidates. But I do offer private counsel and perspective to any candidate who asks for it. I have done this with many candidates in the past. In this election cycle, I know most of the candidates on both sides who are running for president, and many have been friends for years, but they all know that I never endorse."

Throughout the years, Warren has counselled and given advice to different political figures, and have even struck up a close friendship with some. However, the pastor refuses to be acknowledged as either "left-wing" or "right-wing," and instead insists that he is for the "whole bird."

Prior to his church calling, Warren actually envisioned an active involvement in politics. In Jeffery Sheller's 2009 biography called "Prophet of Purpose: The Life of Rick Warren," it was revealed that Warren actually dreamed of becoming president of America.

However, he had a change of heart when he realised that there are more opportunities to change people's lives through the church.

"I realised that you can't legislate a change of heart. You can't change society through laws if people want to break them," Warren said, according to Sheler's book. "To really make a difference in the world you need to change people's hearts, and only Christ can do that. So that is what I began to care about."