Britney Spears has credited prayer with getting her through the anguish of her conservatorship.

The pop star battled for years to have her conservatorship terminated, claiming that it was abusive.

The conservatorship controlled her personal and financial affairs for 13 years before it was finally ended by an LA judge in November.

Writing on Instagram, Spears told her 38 million followers, "God's always with us," and encouraged them to pray "when life gets hard".

In a lengthy post, she opened up about how she felt so challenged by her circumstances that she even stopped believing in God for a while. 

She described feeling "shallow" when a woman was questioning why God would let her daughter die of cancer, and Spears tried to comfort her by telling her "God is with you".

"I know the pain of not believing anymore and feeling so alone and even the arrogance of the world can test your faith," Spears wrote.

"Trust me, I know and it's not fun." 

But she said the last year had been "growth" for her. 

"Did you know the closer you are to God there will always be more tests ... everywhere," she wrote. "A relationship with God is never ending ... that's why prayer is a constant in my life." 

She concluded her post by telling her fans to "pray ... pray ... pray". 

"I'm extremely insecure and I probably care too much so that's all I got ... prayer," she said.