We know that "faith is speech, action, and belief." Is one who is content with the action of the heart considered a believer?

Question:
He says: Honorable Shaykh, may Allah grant you success. Faith is speech, action, and belief; it increases with obedience and decreases with disobedience. Is one who is content with the action of the heart, without the action of the other limbs, considered a believer?

Answer:
No, he is not a believer. The disbelievers have belief; they believe in their hearts. We know that "what they say will not grieve you; indeed, they do not disbelieve in you, but the wrongdoers deny the verses of Allah." Faith is not by the heart alone, nor by the tongue alone, nor by the tongue and heart alone without action. The three matters are necessary.