Is it permissible to allow a Christian domestic worker to read the Gospel in the house, and would I bear a sin for that?

If the wife reads the Gospel, the husband is not obliged to order her to be silent, because Islam acknowledges the People of the Book in their religious practices. However, if she preaches what she reads, then she must be removed from the house and the country. The Muslim is advised not to allow anyone into his house except those whose faith and trustworthiness he trusts.