Can wife change the religion of my child without my consent

Age of the child?IMO baptism ideally requires only mothers name, and fathers name or consent is optional. You may ask the particular church to provide you a copy of the certificate. You need to furnish a reason why you need it and carrying a proof of relationship is advisable like birth certificate/municipal record etc. In the case of divorces in inter-religious marriage if the custody of child is not yet decided then either parent cannot change religion. Even if changed then after divorce it can be nullified. Wait for experts to comment.