All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
The sole act of going to the temples of non-Muslims does not constitute disbelief in Allaah. Disbelief is not a trivial matter, and it is for this reason that a Muslim is not deemed a disbeliever for the slightest reasons; rather, he is not deemed a disbeliever even if he commits an act of disbelief until the truth is clarified to him and decisive arguments are presented to him. Allaah says (what means): {And Allaah would not let a people stray after He has guided them until He makes clear to them what they should avoid. Indeed, Allaah is Knowing of all things} [Quran 9:115]
For more benefit on the conditions of declaring someone a non-Muslim, please refer to Fataawa 8106 and 87963.
If it is confirmed with certainty that someone is a Muslim, then his leaving the religion cannot be confirmed except with the same certainty. Therefore, you should not pay any attention to any satanic whispers by which the devil whispers to you that you have become a non-Muslim, or that your marriage has become invalid and so forth. You should not get carried away with those thoughts, and you should seek refuge in Allaah from the whispers of the devil. Please refer to Fatwa 177059 to which we have referred you previously.