Today, on what marks his last birthday as president of the United States of America, Barack Obama turns 55-years-old.

Throughout his presidency Obama has had to defend himself against accusations that he's not a committed Christian or even a Christian at all. But over his two terms and eight year tenure, there have been numerous occasions where he has visibly and vocally proclaimed and made reference to his beliefs.

Here are four quotes which reveal some of what he's had to say about his Christian faith over the years.

Speaking during his final annual sermon to Washington's elite in February this year, President Obama said this about faith's power over fear...
"Fear does funny things. Fear can lead us to lash out against those who are different. Or lead us to try to get some sinister other under control...Faith is the great cure for fear. Jesus is a good cure for fear."

In an interview with Washington National Cathedral magazine in 2012, Obama said this in response to a question on the role that his faith plays in his life...
"First and foremost, my Christian faith gives me a perspective and security that I don't think I would have otherwise: That I am loved. That, at the end of the day, God is in control—and my main responsibility is to love God with all of my heart, soul, and mind, and to love my neighbor as myself. Now, I don't always live up to that standard, but it is a standard I am always pursuing.

"My faith is also a great source of comfort to me. I've said before that my faith has grown as president. This office tends to make a person pray more; and as President Lincoln once said, 'I have been driven to my knees many times by the overwhelming conviction that I had no place else to go.'

"Finally, I try to make sure that my faith informs how I live my life. As a husband, as a father, and as president, my faith helps me to keep my eyes on the prize and focus on what is good and truly important."

When asked in the same interview if there were any scriptural, passages, prayers or words of wisdom that he often turns to, Obama replied...
"I do have a few favorites. Isaiah 40:31 has been a great source of encouragement in my life, and I quote from it often. Psalm 46 is also important to me; I chose to read it on the tenth anniversary of 9/11. Niebuhr's serenity prayer is a good one as well. I've also been blessed to receive a daily devotional from my faith advisor, Joshua DuBois, who will send me Scripture or thoughts from people such as C.S. Lewis or Howard Thurman every morning."

During an address to Albuquerque residents in 2010, Obama said the following about his own personal journey to faith...
"I'm a Christian by choice...My family, frankly, they weren't folks who went to church every week. My mother was one of the most spiritual people I knew but she didn't raise me in the church, so I came to my Christian faith later in life and it was because the precepts of Jesus Christ spoke to me in terms of the kind of life that I would want to lead. Being my brothers and sisters' keeper, treating others as they would treat me, and I think also understanding that Jesus Christ dying for my sins spoke to the humility we all have to have as human beings, that we're sinful and we're flawed and we make mistakes and we achieve salvation through the grace of God."