What's Oprah Winfrey's spiritual legacy?

After a memorable 25-year run, Winfrey will be leaving daytime television with a more quiet and personal show of simply thanking her viewers.

It's the finale episode of one of the world's most powerful women that millions of people are expected to watch today. With a wide fan base and a long list of celebrity supporters, her influence is undeniable.

But some have gone as far as to deem her as a sort of spiritual leader.

And her "gospel" message all these years has been about "you", observed Kathryn Lofton, author of Oprah: The Gospel of an Icon.

Lofton, assistant professor of American studies and religious studies at Yale, told Salon.com that the "good news" that she has been sharing for more than two decades is "that if you take hold of your life, if you discover (as she says) your best life, anything is possible".

Additionally, "the good news is her revelations about her best life lived, she says, in service to you," Lofton added.

Winfrey's spiritual guidance appealed to a wide audience as they saw her as someone outside established power and religion.

"This is a religion for those who don't want to be religious, but want to feel revelation," Lofton explained to Salon.com.

Winfrey's spiritual teachings have been a concern for Christians.

Apologists Josh McDowell and Dave Sterrett penned a book in 2009 entitled "O" God: A Dialogue on Truth and Oprah’s Spirituality. They not only saw Winfrey as a leader with influence but they also saw the religious landscape in America shifting away from dogma and toward a vague spirituality.

And Winfrey became that spiritual leader that Americans embraced.

Warning Christians about her message, McDowell outlined the differences between what Christianity teaches and what Winfrey presents.

"The Christian God is a personal creator God which all truth resides, who is totally outside of ourselves and outside of our universe," he said last year to churchgoers.

"When Oprah and others refer to God, it is an impersonal force. And I think one way that comes out is that they will say, 'Look within you and find yourself from within. Find that God-consciousness. That is God.'"

During her first A New Earth Web seminar in 2008, Winfrey presented what the Christian apologists have called a dangerous teaching.

The famed talk show host offered a new perspective on Jesus Christ as she promoted Eckhart Tolle's A New Earth: Awakening to Your Life’s Purpose, saying, "I thought Jesus came, died on the cross, that Jesus' being here was about his death and dying on the cross when it really was about him coming to show us how to do it, how to be, to show us the Christ-consciousness that he had and that consciousness abides with all of us."

There were other controversial moments on her show that left Christians concerned.

Also in 2008, she had a lively verbal exchange with a member of the audience when she suggested there were multiple paths to God.

"One of the mistakes that human beings make is believing that there is only one way to live and that we don't accept that there are diverse ways of being in the world and there are millions of ways and many paths to what you call God," Winfrey said.

"Her path might be something else and when she gets there she might call it the light but her loving and her kindness and her generosity, if it brings her to the same point that it brings you, it doesn't matter whether she called it God along the way or not."

Irked by Winfrey's statement, an audience member stepped in to the debate, saying there is only one way and that is through Jesus.

Winfrey rejected the woman's argument.

"There couldn't possibly be just one way. You think if you are somewhere on the planet and you never hear the name of Jesus but yet you live with a loving heart as Jesus would have had you to live but you are on some remote part of the earth and you never heard the name Jesus, you cannot get to heaven you think?" Winfrey posed.

The Secret was also a point of controversy on The Oprah Winfrey Show. She introduced the book by Rhonda Byrne that some called a self-help scam in 2007. The book emphasised positive thinking and living your best life through the idea of the law of attraction – where positive thoughts attract positive events and negative thoughts attract negative events.

Despite the criticism, Winfrey still touted the message and embraced the idea of being responsible for one's own life.

She told Larry King on CNN at the time that the message of The Secret is "the message that I've been trying to share on my show for the past 21 years. The message is that you're really responsible for your life ... The way you think creates reality for yourself."

Her vague and inclusive spirituality message continued with a panel discussion in 2009. She and a few religious leaders tried to relay to her audience a message about being connected, about being spiritual entities, and that their purpose is greater than their profession.

"There is a calling on your life," Winfrey said.

The influential celebrity illustrated that she wholeheartedly embraces that message.

She told Barbara Walters in an interview last year as she reflected on her 25-year career as a talk show host, "I am seeking the fullest expression of myself as a human being on earth."

Her prayer to God, she said, is "use me til you use me up".

She also explained her purpose to CNN this way: “This isn’t about me. I am the messenger to deliver the message of redemption, of hope, of forgiveness, of gratitude, of evolving people to the best of themselves. So I am on my personal journey. My personal journey is to fulfil the highest expression of myself here as a human being here on earth.”

Though Winfrey has impacted and changed many lives, Christian leaders believe that ultimately what she has offered is empty.

"Oprah offers forgiveness without atonement ... She promises meaning without truth, acceptance without judgment, and fulfilment without self-denial," said Dr Albert Mohler, a preeminent evangelical, in an earlier blog post.

Though after Wednesday, she will no longer be on daytime television, Winfrey is still not far from the television scene, having launched her own television network, OWN, at the start of this year.