是动词believe的过去式和过去分词，中文意思是相信，认为

They believed she was possessed by devils.他们认为她是魔鬼附身。

We believed our love was inviolate.我们相信我们的爱是不受亵渎的。

He believed in marital fidelity.

他赞成对婚姻忠实。