What is the ruling on a Muslim partnering with his Christian associate in a business related to churches, knowing that the Christian associate participates in Islamic activities without reservation?

It is permissible for a Muslim to partner with a Jew or a Christian in a permissible endeavor that does not involve financial impropriety. However, it is not permissible for him to participate in building houses of disbelief, such as churches, or designing them, or promoting them.