More than two years after losing his son to a rare form of cancer, actor Gary Sinise is opening up about the faith that has helped his family through unimaginable heartbreak and the precious gifts his son left behind.

The Forrest Gump star, 71, recently spoke with PEOPLE about the loss of his son Mac, who died January 5, 2024, at just 33 years old following a lengthy battle with chordoma, a rare form of bone cancer.

For years, the Sinise family prayed for Mac’s healing. Although the outcome they hoped for never came, Sinise believes his son’s life showed God’s grace in other ways.

“We didn’t get the miracle we were all praying for, but there were other miracles, like the way Mac lived his life. He sure showed us grace under fire,” Sinise shared.

Sitting alongside his wife, Moira, and their daughters, Sophie and Ella, Sinise reflected on the family’s grief, Mac’s strength during his illness and the role faith continues to play in their lives.

During the conversation, Moira held rosary beads as Sinise read from a book of St. Augustine’s prayers that Mac had given his mother. The gift has become one of several reminders of their son’s love and the faith they shared.

Mac’s cancer diagnosis came in 2018, during an already difficult season for the family. Moira was undergoing treatment for breast cancer when doctors discovered that their son had chordoma.

While Moira eventually went into remission, Mac endured years of surgeries, treatments and physical limitations.

But even as his health declined, Mac refused to give up the things that brought him joy.

A gifted musician who studied songwriting and composition at the University of Southern California, Mac had played drums for years. When his illness made drumming impossible, he learned to play the harmonica and continued composing music from his bed.

He also cherished quieter moments, including watching Chicago Cubs games and praying with his mother.

Following Mac’s death, Sinise explored his son’s digital files and discovered unfinished musical compositions, personal letters, videos and messages Mac had saved for the people he loved.

Those discoveries have since become a source of comfort and another way to keep his son’s memory and faith alive.

With help from Mac’s friends and fellow musicians, Sinise has continued bringing his son’s compositions to life. The latest collection, Resurrection & Revival: Part Three, completes a three-disc project featuring 31 compositions shaped by Mac’s musical ideas.

Sinise served as executive producer, and all album sales will benefit the Gary Sinise Foundation, which supports military veterans, first responders and their families, a mission Mac cared deeply about.

The actor is also sharing his family’s journey through grief, love and resilience in his new memoir, Graceful Warrior: The True Story of a Son, a Father, and a Family Who Carried Each Other Through, scheduled for release November 10.

“I hope the resilience I write about will help someone else find their own kind of courage,” Sinise said.

Although the pain of losing Mac remains, the family is finding moments of happiness together. During a recent gathering at their home outside Nashville, all six grandchildren swam while Mac’s music played.

For Sinise, those moments reflect something his son wanted for the family he loved.

“He wanted us to be strong and to continue to live,” Sinise shared.

The family may not have received the healing they prayed for, but Mac’s letters, music and prayer book still offer comfort. Through their shared faith, the Sinises are finding the strength to honor his wish and carry his love and legacy forward.