In order to preach to Christians, MDs invite them to their mosques or homes. And sometimes those Christians invite them to their churches. While they are praying, sometimes they stand and sometimes they sit. Should an MD also stand while they are praying and standing? It all depends on what is the significance of that posture. If they are worshipping Jesus Christ, peace be upon him, as son of God, and this is a sort of homage to him, which they give him while standing, then it is positively forbidden.
No question of your participating in it, whatever they may think. And in that case, you better tell him before you go there, that this is my religion, I will not permit my religion to be interfered with. Otherwise, I will, of course, offer you full respect in every other way. But apart from that, any homage paid to God Almighty alone can be shared.
This is the significance of ta’ala wa ila kalimatin sawaim baina nawa bainakum If the Holy Qur’an tells Prophet Muhammad, peace be upon him, to invite them to this common factor, that means, if they invite you, you should also respond in the same manner. So, as far as the worship of God is concerned, that fundamental, central, significant factor, worship of God, is a common property of all mankind. And that can be shared.
