Elvis and Religion
Elvis and family were a devout Christian family, attending the Assembly of God Pentecostal Church in Mississippi every Sunday where three-year old Elvis would occasionally run over to the choir and sing his little heart out. He simply loved to sing, and Gospel songs were always his favorite, even as a child.
As he grew older, Elvis read the Bible, keeping it close to him and memorizing all the Chapters and Verses, the memory of which stayed with him until his dying day. His favorite was 1 John and the last Gospel. He had an affinity to the name "John," the name he chose for several aliases throughout his career.
Elvis remained always faithful to Jesus. After his family had left the Pentecostal Church upon moving to Memphis, they began attending the First Assembly of God Church in Memphis, and eventually Elvis started attending The East Trigg Baptist Church located in South Memphis at the corner of Hemlock Street and East Trigg Avenue (no longer there). Following the death of his beloved mother, Elvis sought solace in his faith, followed by a quest to understand the deeper meaning of faith, keeping faithful in the reading of his Bible. 
As his star continued to rise, the loss of his mother penetrated his soul deeply and harbored there a void that seemed never to heal. His lingering quest for answers to God's true plan became an obsession as Elvis, influenced by others, sought a spiritual path that lead him to the study of other faiths, traditions and customs including Eastern philosophies and the spiritual studies of Paramahansa Yogananda, the Hindu mystic, yogi and guru. When Elvis learned that a great-grandmother on his mother's side, Martha Tackett Mansell (1851 - 1896) was Jewish, he began wearing a Star of David around his neck and donating anonymously to a local synagogue. His hairstylist and friend, Larry Geller, who was Catholic, taught Elvis things about the Catholic faith which Elvis' found inspiring, and also taught him different aspects of spirituality. While Elvis did remain a Baptist for the remainder of his life, there were moments when he felt drawn to the Catholic faith and began to incorporate some of those traditions and teachings into his spiritual journey. His wife, Priscilla, was Catholic. He did have Catholic friends including Geller, and a leading lady, Dolores Hart, who later became a Benedictine Nun, and as of this writing, is now Mother Superior. Former girlfriend, Linda Thompson, was also Catholic.
So, what did Elvis take away from the knowledge about the Catholic faith? Barbara Lee: "Elvis once asked me if I was Catholic. He told me he had gone into a few Catholic Churches and that they were very beautiful." He particularly found the rituals and traditions of the true Church quite compelling. According to a blog from Our Lady of Lourdes Catholic Church in Milton, Hampshire, England,"Father Gilbert Hartke, a Catholic priest and founder of the drama department at The Catholic University of America, was another significant influence. Elvis met Father Hartke during the filming of "Change of Habit" in 1969, where Elvis played a doctor in a Catholic clinic. Father Hartke served as a consultant for the film, and his discussions with Elvis reportedly left a lasting impression."
Elvis displayed a fondness for Catholic Saints, especially Saint Jude, Patron of lost causes. After someone had given him a statue of Jesus, Elvis made a small altar in his bedroom where he placed the statue and where he would often pray.
Miracle of the Rosary
Only Elvis knew why he chose to record the song "Miracle of the Rosary" ten years after it was written by a friend from childhood, Lee Denson, who wrote the song in 1960 after both he and his wife converted from Pentecostal to the Catholic faith. Denson said not only did Elvis like the song, he kept it. It would not surprise if Elvis beheld a secret devotion to the Blessed Mother. After all, he loved the Lord with all his heart, why not His mother? When he finally recorded the song in 1971, Elvis sang the beautiful words adding a deep sense of contrition to the mood.
Elvis Presley once stated that had he not been an entertainer, he would have become a preacher. He would keep a stack of Bibles in his trunk which he would hand out to people he knew and strangers he met. One of Elvis' co-stars, Deborah Walley, said she went on a date with Elvis and he spoke mainly about the Bible and faith. His soul was definitely filled with the Lord, and his voice...a true gift from God.