If the Islamic Dawa is a legitimate right for us, and fighting non-Muslims is a protection for it, then why do we fight other religious and Western Dawa reaching Muslims, which their proponents consider to be true? And how can non-Muslims be convinced that our religion is the truth and all others are false?

It is not permissible for a Muslim to engage in dialogue with the enemies of Islam unless he is firm in knowledge and faith. A Muslim must be convinced that his religion is the truth, and he should focus in his dialogue with non-Muslims on matters of faith and the introduction of Allah Almighty, because their acceptance of God's existence will make it easier for them to understand the rulings of Islam. If it becomes clear to the disbeliever that Islam is the truth, he will understand why other ideas should not be enabled, because the matter concerns an afterlife destiny, and because preventing these ideas achieves the greatest interest, which is the preservation of religion.