Deen.
Code-law or system, which comes from Allah alone.
The true way (deen) with God is Al-Islam (submission to his will), and the people of the Book did not differ until knowledge (of this revelation) had come to them, out of mutual opposition. But those who deny the signs of God should remember that He is swift in the reckoning. (3:19).
And whosoever will seek a way other than Islam, it shall not be accepted of Him, and he shall be of the losers in the Hereafter. (3:85).
Who would be more unjust than he who invents a lie about Allah while he is being called to Islam? Allah does not direct such evildoing folk in the right way.
Religion.
A passage or path made by man.
Religion can be defined as the belief in and worship of gods or any such system of prayer and faith. Religious rituals usually involve dance and music; they are also very verbal since the sacred truths must be stated.
Here’s what the Quran says about their worship/prayer.
And their prayer at the house is nothing but a whistling and a clapping of hands; therefore, taste you now the chastisement for your unbelief! (8:35)