The tithe has an interesting timeline in Christian history. Cyprian (200-258) was the first Christian writer to mention tithing in regards to support of the clergy. He offered this as a suggestion, and viewed tithing to Christian clergy as voluntary and the least a Christian could do.
For approximately 300 years, the church did not tithe, they gave, and they gave generously, but they never tithed. It wasn't until Constantine became emperor and Christianity became institutionalized that tithing to the church was even seriously considered. And even then, it wasn't until the eighth century that tithing became widespread in the "Christian" institution
When this error was introduced in the third century, the concept was first adopted by an orthodox Church,then it was voluntary in nature. But, at the Synod of Macon in the year 585 A.D., payment of tithes was made compulsory under threat of excommunication. Secular authorities were then used to enforce this demand and the professing Christianity today accept the teaching.