Savannah Guthrie will "never stop looking" for her missing mom Nancy.

The Today show presenter's 84-year-old mother Nancy Guthrie disappeared from her Arizona home on February 1 and police have been treating her disappearance as a kidnapping. Savannah has previously admitted she believes Nancy is no longer alive but she is adamant she won't give up the search until she is able to bring her mother home.

In a post on Instagram to mark Mother's Day in the US, Savannah wrote: "We will never stop looking for you. We will never be at peace until we find you.

"We need help. Someone knows something that can make the difference. Call 1800CALLFBI. You can be anonymous, and the reward remains available. Please keep praying. Bring her home."

Savannah previously confessed she's accepted Nancy is no longer alive after receiving a message from a higher power.

During an interview with her Today show colleague Hoda Kotb, Savannah cried as she explained: "Early on, I felt that I heard, one of the very few times in my life, I did hear God speak to me.

"As I said to myself: 'I can handle anything. I just can't handle not knowing ... I have to know'. And I heard a voice and it said: 'You do know where she is. She's with me.'

"So whether she's on this Earth still or whether she's in Heaven, I know where she is. I know who she's with. But we need to know. "

However, Savannah has admitted struggling with her Christian faith after failing to find answers in her search for Nancy.

In an emotional message as part of Good Shepherd New York's digital Easter gathering in April, she said: "Good morning, everybody. Happy Easter. "And Easter is happy. It is flowers and pastels and baby bunnies. It is sunshine and joy and hope. It is rebirth and second chances and new life and fresh starts.

"It is the most important day of the year for all of us who believe, even more than Christ's birth, more than his death. His resurrection, his second birth into a permanent life, that is what is most crucial to us.

"His revival and resurrection means the same for us. We celebrate today the promise of a new life that never ends in death.

"But standing here today, I have to tell you, there are moments in which that promise seems irretrievably far away, when life itself seems far harder than death.

"These moments of deep disappointment with God, the feeling of utter abandonment for most of us, there will come a time in our life when these feelings hold sway."

The broadcaster noted that despite being taught that Jesus "experienced every single emotion that we humans can feel", her recent heartbreak has made her question "whether Jesus really ever experienced this particular wound that I feel".

She described it as a "grievous and uniquely cruel injury of not knowing, of uncertainty and confusion and answers withheld in those darkest moments".