[a] Confession/repentance; [b] adoption/election/justification.
A couple of things catch my eye here. The first is that justification happens under baptism, and not under belief. Since there is no proxy for adults, what is done with verses like these:
Rom. 5:1-2 : 1 Therefore, since we have been justified through faith, we have peace with God through our Lord Jesus Christ, 2 through whom we have gained access by faith into this grace in which we now stand. And we rejoice in the hope of the glory of God.
The other thing is that election "happens" at Baptism. What does this mean? (I think election happens for each of the elect all the way back at the beginning, and the elect become aware of it at belief.)
It is almost unbelievable that the Protestants would claim that the early Church, closest to the Apostles, would practice something the Apostles would disapprove of.
Oh, I don't know, it has been pointed out to me that many of the epistles were answers to questions, meaning true followers didn't know what to do on certain subjects. Why should we assume that the early Church had its act completely together right after the Apostles were gone? It seems reasonable that, from church to church, there were many mistakes made and much error taught. I don't mean in a sinister way, but just because they didn't know any better yet.
Even your side will agree that God gives us faith. The second verse makes that clear: through Jesus Christ we have gained access to faith into this grace. This does not specify any age of reason or being able to recite prayers. God changes our hearts; whether we follow in His footsteps, or reject God does not invalidate His gift. Nor does it mean, as Reformers read it, that faith is something we receive when we are adults. Our hearts are changed at Baptism. Whether we live a Christian life from thereon is our choice.