I write to you, fathers, because you know him who is from the beginning. I write to you, young men, because you have overcome the evil one. I write to you, little children, because you know 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. 