Salaam,
Brother there is a lot of information on the Council of Nicea and the Council of Trent. They are worth investigating. The words of the creeds of Christianity were selected and there was debate about transubstantiation. This is important as the nature of commuion was debated. Hence when a Christian partakes of Holy Communion they are actually drinking blood and eating the body of Christ.
Usually most Christians are not educated on the nature of Holy Communion, yet on Sundays that is the focus of the service. This is where the forgiveness of sins comes from. To be forgiven for sins you drink the blood and eat of the body of Christ. This is not symbolic. I repeat this is not symbolic.
Muslims are constantly asked to defend Islam and we can. Most Christians will not be able to defend the nature of transubstantiation. They often think we are making it up. The Evangelicans and splinter Protestant groups will deny the nature of communion. Yet, in the Church annals these synods were held and to this day are the backbone of Christainity.
Please do not doubt me. I have spent many decades and have found the Truth. I will not give you internet sites. There are many scholary works on both the councils and transubstantiation. They can be found in libraries and seminaries.
I pray this was of use to you.