What is the ruling on working with a car that a brother acquired from a church with a contract obligating him to convert to Christianity and proselytize for it? Is it obligatory to destroy it or return it to the church? Is it permissible to benefit from this brother's earnings?

What was mentioned about the brother is considered apostasy from the religion of Islam. The car must be returned to the church to terminate the forbidden contract, while continuing to advise the brother to repent to Allah and not despair of his guidance, and to seek help from those who can counsel him well, explaining the virtues of Islam and the danger of apostasy from it.