It's interesting that Hays presumes to advise on hermeneutics, when he plummets head-first into a flub that no one year seminary student is bound to committ. He proof-texts Acts to contravene the didactic Pauline teachings on sound speech. Hays therefore assumes scripture is incoherent, and is content to leave it at that without cross-text harmonization. It is a 101 elementary point of fact that the nature of historical narrative (i.e., Acts) is descriptive not prescriptive.
If the gospel is encapsulated in the brief phrase, "Believe in the Lord Jesus, and you will be saved" (Acts 16:31 TNIV), then I see no other alternative than to admit that infant baptism (as described by the Reformers) is an affront to the central tenets of the gospel. Again, Schreiner explains:
"For some believers today the connection of baptism to conversion seems odd, for they associate conversion with belief, making a profession of faith, or even going forward at an evangelistic event. Baptism is separated from conversion because many were baptized long before or after their conversion. But in the NT era it was unheard of to separate baptism from faith in Christ for such a long period. Baptism occurred either immediately after or very soon after people believed. The short interval between faith and baptism is evident from numerous examples in the book of Acts (Acts 2:41; 8:12-13; 8:38; 9:18; 10:48; 16:15, 33; 18:8; 19:5). It follows, then, that when Paul connects death to sin with baptism, death to sin takes place at conversion, for baptism as an initiatory event occurs at the threshold of one's new life. Paul appeals to baptism because it dramatically represents the washing away of one's sins and the new life to which believers are called."4
i) Notice that Billy Birch, in his approving citation of Schreiner, as well as his own citation of Acts, doesn't hesitate to use the historical narrative Acts as prescriptive rather than merely descriptive. He uses Acts to establish the theory and practice of credobaptism. I guess that Billy committed a flub which no first-year seminarian would commit.
ii) And keep in mind that there's also such a thing as narrative theology. We can't draw a hard and fast line between descriptive and prescription communication.
iii) I'd add that his disjunction between Pauline discourse in Acts and Pauline teaching in the Pauline epistles is futile since we also have examples of harsh Pauline discourse in the Pauline epistles. So, he can't draw a bright line between the historical genre and the epistolary genre in that respect.
"Moreover, even if Paul uses harsh language in a context of historicality, his speech is a product of God's omnicausality, thus it is itself inspired."
Yes, inspired discourse. And why should inspired discourse never be a model for Christian discourse? Should uninspired discourse be the model for Christian discourse?
If Hays thinks that he is well qualified to appertain such contextualization, let him tell us how he too attains the property of the divine self-representation that changes his flesh-induced bombasts into one of divine approval, in a passage that is historically and culturally conditioned.
i) To begin with, don't we need to be careful about blanket dismissals regarding the culturebound nature of Biblical statements? Isn't that what liberals always say about the Bible? Don't we need to stake out a considerably more qualified position?
After all, the Pauline epistles are occasional writings. Prompted by a particular sitz-im-leben. Should we also dismiss "didactic Pauline teachings" as culturebound?
ii) In addition, NT writers use commendatory language as well as condemnatory language. If we're never permitted to emulate the condemnatory language of Scripture, then we're never permitted to emulate the commendatory language of Scripture. Neither praise nor blame.