All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.
Sitting with the non-Muslims when they defame and insult the religion is forbidden because Allah Says (what means): {And it has already come down to you in the Book that when you hear the verses of Allah [recited], they are denied [by them] and ridiculed; so do not sit with them until they enter into another conversation. Indeed, you would then be like them.} [Quran 4:140]
Therefore, if this non-Muslim or others do not stop insulting or defaming the religion, then it is neither permissible to sit with them nor to play with them.
In case he stops this defamation, then if you hope that by sitting with him and playing with him, you hope that his heart will be softened towards Islam, then you may play with him.
However, if you do not hope anything of this kind, then you should look for someone else who do not commit such grave sins so that your heart will remain alive honoring the rituals of Allah and hating His Enemies.
Allah Knows best.