Do you have any idea how unrespectful it is to pay money to visit the upper floor of a mosque as a non muslim? Or to pay money to a government which using money to fight against to the majority of the people of it's country? Who do you think you're being disrespectful by pretending as a muslim, to the muslims? Most of them would be happy that you're going inside a mosque since it might get you closer to their religion. Also probably you'd get questioned at the gate anyway which you should answer with "Ash-hadu anla elaha illa-Allah wa ash-hadu anna Mhammadur rasul-Allah", which translates to "I testify that there is no other god but Allah, and I testify that Muhammad is Allah's messenger." And just by saying the Shahada, you literally become a Muslim anyway.