Translation

熱烈な / 心からの / 強い信念を持つ

Meaning

Fervent describes a feeling, belief, wish, or supporter that is intensely sincere and deeply felt. It is often positive or respectful, not merely loud.

Examples

• 彼女は平和への熱烈な願いを語りました。
  She spoke of her fervent hope for peace.
• 彼はその改革の熱心な支持者です。
  He is a fervent supporter of the reform.