I don't know what is said in context of the quote, so I don't know what (if any) elaboration is included by the writer.
I would say: no articulation of the doctrine of baptism may stand alone without (implied at least) a fully developed doctrine of sacramentology.
Where, in relation to the above quote, is the distinction between the sign and the thing-signified? That is what I want to know. For example, the Rom 6:4 reference. Is Paul supposed to be talking about a
human rite which is in eternal coincidence, in every single case, with
Holy Spirit's own baptizing function? Because, as we all (should!) know, Holy Spirit unites us to Christ in his effectual calling. The baptism of
the Spirit does that, and
not the application of water.
The connection between Holy Spirit's work and the church's work is called a "sacramental union." And it is mysterious, and we bow before its mystery while seeking deeper understanding. Here is how WCF 28:6 addresses the issue:
The efficacy of Baptism is not tied to that moment of time wherein it is administered; yet notwithstanding, by the right use of this ordinance, the grace promised is not only offered, but really exhibited and conferred, by the Holy Ghost, to such (whether of age or infants) as that grace belongeth unto, according to the counsel of God’s own will, in His appointed time
Often these days, we hear people who call themselves Reformed, and who insist on objectifying the sacraments (virtually adopting Lutheranism at best, and Roman views at worst), who call attention to the first
bolded clause above, while dropping (or ignoring) the latter clauses (also
bolded), up to and including the final. Well, they all go together!
Thus, because
faith's function in baptismal efficacy is indispensable, because election, regeneration,--indeed ALL the benefits of redemption--are sealed to believers exclusively, we differentiate between what we can see and what we can't, between Holy Spirit's work and ours, and do not claim for the water or the church what belongs only to God.
Now, I think I detect, from the final sentence, that this statement was worded in opposition to a baptist view of baptism (ref. to baptism's portrayal of past Spirit-activity).
However, it should be noted that one particular use of a doctrinal affirmation to oppose what
may be viewed as an error in one direction, cannot be simply turned around and wielded in essentially the same fashion against those who err (supposedly) in
another direction.