を信じなかった

didn't believe

→ を
phrase Rare #21,372
didn't believe Used after a person, statement, or claim to say that someone did not believe it. The を marks what was not believed.
JA: 私は彼の言い訳を信じなかった。
EN: I didn't believe his excuse.

最初は誰もを信じなかった

At first, no one believed me.

彼らは最初彼の言う事を信じなかった

They didn't believe what he said at first.

誰も彼の話を信じなかった

No one believed what he said.

私はただトムの言ったことを信じなかっただけだ

I just didn't believe what Tom said.

トムを信じなかった

Tom didn't believe me.

トムメアリーが言ったことを信じなかった

Tom didn't believe what Mary said.

警察はトムの話を信じなかった

The police didn't believe Tom's story.

彼はベンの言葉を信じなかった

He didn't believe what Ben said.

彼は正直は最良の策を信じなかった

He didn't believe that honesty is the best policy.

誰もを信じなかった

No one believed him.

— 嵐の中で (2018)