Christianity and Islam and the most widespread Monotheistic faiths on Earth. However, this is not enough in order to be able to say that they are similar. The dogmas of the Holy Trinity and of the two Natures of Christ (one Divine and the other Human) are completely foreign to the Muslims. Moreover, Both practicing Christians and devout Muslims argue that they do not worhip the same God. The Quran forbids the veneration of anything else besides Allah. This is why Muslims do not accept the Eastern Orthodox ways of worshipping the Cross, the Gospel, the Mother of God, Saints, Angels or Relics. This iconoclastic stance and the rejection of the Mysteries of the Church keep the two faiths apart. The aim of this study is to briefly describe Islam’s most important places of worship and their so that it becomes clear that it is not wrong to also emphasize the insurmountable differences between these two Monotheistic faiths.