Is it valid for a church to declare someone a Christian after they complete a set of procedures?
No. Becoming a Christian is not accomplished by completing a set ritual, rules, regulations, or procedure, and a church cannot rightly declare someone a Christian on that basis. Salvation comes by believing the Gospel and personal faith in Christ's death, burial, and resurrection; church activities have their place but are not substitutes.
Les teaches that you do not become a Christian by going through a certain set ritual or rules and regulations or a set procedure. He notes that many denominations, including his own, expect people to go through a set of procedures, and then the church declares them Christians, but he says that is not the case. Instead, we have to believe the Gospel, and then other things have their rightful place. He is in favor of the local church and Sunday school and similar things, but those are not to be used as a substitute for salvation. Salvation has to be by personal faith in the death, burial, and resurrection of Christ. In the surrounding passage, Paul says he labored more abundantly than the other apostles, yet not in his flesh but by the grace of God with him; whether Paul or they, so they preached, and those addressed believed, which brought them out of their paganism.
Therefore whether it were I or they, so we preach, and so ye believed.