Therefore, as for you, let that remain in you which you heard from the beginning. If that which you heard from the beginning remains in you, you also will remain in the Son, and in the Father.

 The first question is easy to answer. There was only one ceremony that all Christians passed through, and that was baptism; it was, indeed, in later days the standard practice at baptism to anoint Christians with holy oil, as Tertullian tells us. 