Calligraphy is an Islamic art that is supposed to serve, honour, and respect the Qur’an by beautifully capturing its verses in a piece of art. That is why there is nothing wrong, as far as Islam is concerned, in hanging posters with Qur’anic calligraphy on the walls of one’s home as long as those posters are treated with respect.
Sheikh Ahmad Kutty, a senior lecturer and Islamic scholar at the Islamic Institute of Toronto, Ontario, Canada, states the following: There is nothing wrong with hanging posters with Qur’anic calligraphy on the walls of our homes provided that we treat them with respect. Although we must never lose sight of the fact that the Qur’an was never revealed for the purpose of decoration but for living by it, the scholars over the centuries have approved such practices, for the simple fact that they act as spiritual reminders for us, engrossed as we are in the many mundane cares and indulgences of material life. It is in this spirit that the Muslim Ummah has tolerated and even encouraged such practices.

So there is no need to condemn them as innovations, for they serve a good purpose; after all, they are much better than other profane decorations that people often hang on their walls.
We are always on safer ground if we do not judge such matters too harshly, either permissively or rigidly. They are fine so long as we do not go to extremes and provided that we do not end up disrespecting Allah’s word.