Titus 1:9

As he hath been taught] RV (which is lit.) 'according to the teaching'; i.e. the teaching which he has received, perhaps referring to a gradually forming statement of the essentials of the faith, such as culminated, in the 2nd cent., in the 'Roman symbol,' or early form of the Apostles' Creed.

10. Here begins the arraignment of the false teachings which the elders will have to meet (Titus 1:10). They of the circumcision] i.e Jewish converts who insisted that to be a Christian one must also submit to Jewish ordinances.