There's this little throw-down opening up at Doug Wilson's blog over what credobaptism "means", and one commenter tossed out this doozy:
A word about baptistic baptism. I grew up in the Church of Christ, where, even though they'd rather be stoned to death than be called a "Baptist," nevertheless their concept of baptism is uber-baptistic.

There is more to the credo part of credobaptism than just a "background check," or even "confirmation." Underlying the baptistic concept of baptism is the philosophical premise that God does not interfere with the unadulterated, absolute free will of men (who, by the way, are morally tabula-rasa at birth).

In other words, credobaptism, at its foundation, is an explicit denial of both God's sovereignty in the area of human will, and the fact that man is dead in sin. This is why it is so repulsive. And this is primarily why I left the COC ("this" being the denials, not the symptomatic credo-stuff).

So when a COC elder or a Baptist pastor starts the interrogation, what they're looking for is: 1)some kind of evidence that the baptismal candidate has reached the mental age where (the philosophical argument goes) she can be reasonably expected to exercise a high level of beloved rationality, and 2)some evidence that the candidate has in fact used her rational ability to remove her own heart of stone and replace it with a heart of flesh (all by herself).

Uuugghhhh... I believed that stuff for 30 years...
Yeah. Whatever. My first response was that this was dumb-factor of 12 on a scale of 5, and I invited our blog friend here to D-Blog this subject, but he passed. Instead, he wanted to know where his opinion went south, and I told him something like what follows.

That said, the "interview" is seeking evidence of faith. Just like in a paedo church prior to confirmation when they comb over the catechism so as to confirm (hence ...) the evidence of faith, so does the ordained baptist malcontent when he asks for one's "testimony".

Seeking the evidence of faith does not imply the superiority of free will over God's sovereignty. It seeks to announce His sovereign action through Baptism. Baptism is for the faithful not for anyone we hope will get faith.
For example, when John the Alcoholic gets baptized at age 47 because Pastor Abe at First Proper Presbyterian evangelized him at the barber shop, presbyterians would not then go an baptize all of Abe's college age atheist children, would they? Why not -- because human free will is sovereign? Or because baptism is for those in faith? See - if what is at issue is that faith is promised to the children of the faithful, then the age of the person gaining faith shouldn't matter. And that goes double for the classic "household baptisms" defense. "Households" in those days were often extended family deals - so what do we do with that if we go paedo on the one hand?

Those adult kids of John the Alcoholic don't have a reservation at the fount just because Dad is suddenly regenerate: why would the infant kids?
I know there's a WCF answer to this, but it only answers the latter half of the question -- not the former half. It ignores the former half.
The comeback was classic:
Whoa, hoss. First, adults who display an obvious lack of faith are presumed to be unfaithful precisely because all the evidence says that they are. Infant children of covenant parents are presumed to be faithful precisely because all the evidence says they are.

Second, you must recognise that credo-baptism is no more "reliable" a measure of true faith than paedobaptism. In both cases, those administering the sign of the covenant are relying upon God's promises concerning covenant status. John says that no man can say "Jesus is Lord" except by the Holy Spirit (good enough for the credo-b). And Paul says "but now your children are holy" (good enough for the paedo-b). In neither case do you get a signed, notarized certificate, and in both cases you get the occasional bad apple, which apparently is okay with God, if circumcission is any indicator.
See: the presumption that someone has faith because their parents have faith is fine - unless they do things bad by their own free will. Then we can judge them sinners who need to repent. So while LongShot here wants to pin some kind of crypto-pelagianism on baptists, he's a crypto-pelagian as well because of the value he hangs on bad works.

See: what makes us sinners is not the sin we do - it's our nature. We have this sin nature which makes us sinners. And the question is whether there is a faith which lives inside us as a result of Grace. Baptism is a demonstration of what God has done in us, not what he might do in the future.

Last off, there’s no question there are some false credobaptisms. But let’s be serious: is anyone saying there are –fewer- false paedobaptisms? How about in churches ordaining women and openly-gay men? The objection is hollow when we think about what one of the objectives of baptism is – which is that it brings those who are called by God to Him and demonstrates His work upon them.

No seriously: NOW I am going on vacation.