An expert in the history of the Catholic Church, Domingo Ramos-Lissón, explained in an interview that the preparation of the early Christians for baptism could last up to three years, and that many professions prohibited a person from registering as a catechumen.

"If we follow the path taken by someone who wanted to become a Christian in the fourth century, initially we will see a thorough examination of his life, family conditions and aspiring profession," Ramos-Lissón said in an interview with the website PrimerosCristianos.com (First Christians).

In that regard, he explained, "some family situations, such as polygamy and concubinage, or professions, such as theatrical actor, magician, guardian of idols, gladiator and other offices, prevented that person from being considered a catechumen. However, once they changed their lifestyle, they were given the chance to be baptized.

Ramos-Lissón noted that once admitted, the catechumens "could attend the Liturgy of the Word in the Eucharistic celebration."

According to the stories of the fourth century, the preparation lasted at least 40 days and began eight weeks before Easter. "The formation included three aspects: doctrinal, moral and ritual."

However, he indicated that the early sources describe the preparation in the first second centuries.  One reference speaks "of a three year long catechetical instruction."

Ramos-Lissón remarked that during this time, catechumens responded to various concerns including the threat of persecution and the presence of the heretics, "which could confuse the good faith of those who came to Christianity. These factors prompted the Church to bring the catechumens to the test of time and perseverance."