What steps would a non-practicing but fully initiated Catholic have to take to come back to the Church?
This question, while it accounts in a general way for the place of the many people who have gone away from the Church after their confirmation, is not answered with one set of steps – as several factors that are not present in the question need to be discerned. I will therefore trace out multiple scenarios to answer this question – showing how for some the journey is quite simple, while for others it can be more complicated.
Let us begin with the simplest: those who are called “lapsed Catholics” – a fully initiated Catholic who went away from the Church, but is living either a single life (having never married) or is married in a Catholic wedding and is still married. In these cases, all that is necessary would be a return by way of a good confession – including in their confessing among any other sins which they have committed during their time away from the Church that they fell away from the Church, and therefore were not faithful to Sunday Mass for the length of time that they were away and (if true) to an at least once a year confession. Having confessed their sins, they are immediately reconciled without further steps and are able to receive Holy Communion.
Building from the first example, let’s say the person is married once, still married, but that marriage was not by way of a Catholic wedding ceremony (but perhaps in a Christian denomination or even by the Justice of Peace). Such a person would first need to have their marriage union “convalidated,” that is, to have their legal “civil union” receive recognition by the Church by way of having a Catholic “wedding,” even if it is much more simply celebrated than a “typical wedding,” with as few people present as perhaps the clergyman and two witnesses. As part of the convalidation, it is proper to go to confession on that same occasion – thus confessing having fallen away from the sacraments as well as attempting marriage outside of the Church without the Church’s dispensation. After this confession and convalidation, that person would also be readmitted to communion.
Some situations are far more complex – especially when they involve such situations that include marriage, divorce, and attempted remarriage; or in situations where a person who desires to live in full communion remains in a state of life contrary to the Church (such as someone who is not married, but is cohabiting with another [and is thus simulating the married life without the benefit of the sacrament]). These types of situations require further steps. In the case of the cohabiting person, it is necessary that their living arrangement be rightly rectified – which most properly is accomplished by separating when such is possible. If they are unwilling or unable to do such (let’s say because they have one or more children born of the illegitimate relationship), it needs to be honestly discussed with their pastor as to other possible steps (such as marrying, or living in one or another fully chaste manner while still upholding their duties to the children). As for divorcees who are in a second (or subsequent) union, that first union needs to be rightly investigated for its validity ahead of their being brought along to go convalidation of the present union and to their going to confession unto hopeful restoration to communion.
Most certainly other circumstances also exist beyond those presented here – such as that of a person who has been openly and stridently denying of truths of the Catholic faith and then desires readmission to the Church, which may require a public act of renouncing their former denials of the faith. However, the above examples hopefully give you a sense that while some steps (like confession) will always be necessary, full solutions depend on all of the circumstances in the life of each person who desires to return.