Your latest question is a tacit admission that you were unable to find a relative pronoun in verse sixteen in search of an antecedent. Without that imaginary pronoun which you are trying to read into the text there is no scriptural basis for excluding belief in the promise that baptism into Christ saves from the entire correct body of what is to be believed about Christ.
On the other hand, there is nothing in believing the promise that baptism into Christ saves which excludes anything in verse fourteen from the correct body of that which is to be believed about Christ.
The participles believed and baptized tell us of a category or define a set of people who will be saved. The Apostles and disciples who were already baptized and believed are not excluded from that category or set of people who will be saved, that is, they are not excluded from that promise.
For that reason and because the passage does not say, "the one who shall believe and who shall be baptized shall be saved," your assertions and conclusions regarding none have been saved, the timing, and signs is not correct.
According to the text rather than someone's imagination what is the nominative which does now save you? Answer: baptism. What is the passive object being saved? Answer: you.
The parenthetical thought you refer to then refers to the acting nominative, baptism, rather than the passive object, you.
The misunderstanding of Paul previously referred to is your misunderstanding of Paul.
Your interpretation of John 3 ignores the context, baptism. It is even more self evident if a person reads John 1-4.
You're almost there, almost at a right understanding. God very often works through people. This is especially true of the proclamation of the Gospel in word and sacrament.
That is a non clarification of the text under discussion, but it is a nice story.
God put His work in this regard is the hands of men beginning with John the baptist. Baptism is from God and it accomplishes his will just as the gospel preached through men accomplishes His will.
I hope you will read the section above regarding category and set in Mark 16:16. This is because the only one saying God cannot save without baptism is you based upon your misunderstanding of that passage and Scripture in general.