There are some (hypocrites led by Abu Amir, the Christian monk, who eventually went to Rome and encouraged the Caesar to attack the newly established Islamic nation which led to the expedition to Tabuk by Prophet Mohammad) who built their own mosque to use it as a mean to harm the cause, spread disbelief and to cause a division between the believers. They are the ones who have declared war with God a long time ago. Although they swear that they have the best intention, God hereby declares that they are liars.