I cannot say what I believe in

我说不出信仰是什么

believe in 信赖；信仰；

例句：

I believe in seasoning food before putting it on the table.

我认为在把食物端上餐桌前应该先调味。

I believe in the maxim "if it ain't broke, don't fix it".

我相信这样一条箴言：“不破不修”。

He does not believe in a federal Europe with centralising powers.

他认为一个集权式联邦制在欧洲是不可行的。