What comes first, believing the Gospel or church involvement?
Believing the Gospel comes first. You do not become a Christian by going through rituals, rules, regulations, or a set procedure. You must believe the Gospel, and then church involvement and other things have their rightful place. Salvation is by personal faith in Christ's death, burial, and resurrection.
Les explains that you don't become a Christian by going through a set ritual or rules and regulations or a set procedure. Many denominations expect people to go through procedures and then declare them Christians, but that is not the case. He says we have to believe the Gospel, and then these other things have their rightful place. He is in favor of the local church and Sunday school, but they are not a substitute for salvation. It has to be by personal faith in the death, burial, and resurrection of Christ. He then moves into verse 12 on the theme of resurrection.
Therefore whether it were I or they, so we preach, and so ye believed.