Pastor Rick Warren of Saddleback Church is preparing for "the most life-changing [sermon] series" of his career, which is titled "The Miracle of Mercy."

Warren said the series will hopefully help people get through the worst days of their lives by relying on the mercy of God.

"God's mercy has sustained me, and my wife Kay, and our entire family through the darkest days," Warren shared in a video posted on his Facebook page.

Warren was referring to the suicide of his son Matthew, who had a lengthy battle with depression and mental illness. "Easter has become particularly personal and poignant to me in the past three years, because five days after Easter three years ago, my 27-year-old son ended his own life," Warren shared.

"He had battled mental illness since childhood, and despite all the best doctors and the best medicine, therapy, and prayers, and love, he lost his battle for hope on Easter week. And our family was devastated. The day Matthew gave into despair was the worst day of my life," the pastor added.

The Warren family was at a loss then how to move on from their despair, but Warren said that God's mercy helped them move on. He hopes that other families who are facing deep depression will find hope and comfort in his upcoming messages.

Warren said there is but one answer that he can give to people who often ask these three fundamental questions: "What do I do in my days of pain? How do I get through my days of doubt and confusion? How do I get to the days of joy and victory?"

The megachurch pastor said the answer to all of these questions is by "receiving God's mercy."