I wouldn't call him an arch fiend. As FV-friendly goes, he doesn't walk off cliffs in the same way as some of the other proponents do. I think there's a strange lack of Confessional integrity when he's tried to defend statements made by some former PCA pastors as if they were accidentally un-Confessional. I also think his (and others') ideas that the Confession goes a certain distance on the nature of the Sacraments and Union with Christ but that the Bible "fills it out" is filled with difficulties. Primarily, the things he says others are fleshing out are things that the Confession explicitly repudiates.
Let me just say that you can find better resources than Wilson on this subject. It is true that some Presbyterians have neglected hearth and home and the Covenantal responsibility that parent has for child. The cure for neglect is not a hard tack in the opposite direction where faithful parenting becomes a downpayment on a saved child. Nothing is ever quite expressed that way but all the subtlety and caution that goes with how we ought to understand election, the Covenant, and Sacraments is sometimes overshadowed by ideas that are easily confused. Of course, Wilson can always jump back over that line when accused that his language sounds un-Confessional but that doesn't prevent the ignorant and unstable from being led astray by reading his books.
Primarily, when it comes to the Confessional understanding of the issue, Wilson and those of various shades of FV want to make Baptism be the instrument for union with Christ. This is the place where neglect in one area has caused such a hard jerk to the opposite extreme that some drove off the cliff and become almost Romish in their doctrines. They want to be able to declare to their kids and to others: You're elect! Thus, they say that those that are Baptized are united to Christ in some sense. Union with Christ is conditional then upon Covenantal faithfulness: parents do your duty and members make sure you're faithful! If you're not then you will fall out of the Covenant, lose union with Christ (that you had in some sense), and you will no longer be elect.
The Reformed position is that the graces conferred by baptism only belong to those elect. Nobody is united to Christ unless he is elect and faith (not baptism) is the instrument of our justification. Baptism is a ministerial announcement and, though we benefit greatly from its graces, we ought not turn it into more than it is intended. We must preserve the unique benefits that flow from vital union with Christ that the elect alone enjoy. If we do not then we end up blending the things hidden with the things revealed. We end up thinking that men affect God's eternal pleasure for His elect. We end up thinking that we somehow must add our faithfulness to the equation of God's grace rather than simply clinging to Christ in simple faith and allowing the graces of justification to flow out into our sanctification.
The sad truth is that Wilson and others were trying to recover a healthy Covenantal understanding of their kids but, in their hubris, ignored the rich Reformed piety that already existed in the Catechisms and elsewhere that were never the root of the decline. By beating their own path, they ended up losing the Gospel itself. Perhaps Wilson hasn't gone as far as others but I'm convinced his carelessness with some of these truths has led others astray. True evangelical faith is that God justifies the un-Godly. Stop, do not pass Go. True evangelical faith is not that God will wait until you have a fully matured and sanctified faith and then justify you on the basis of the vitality and constancy of your faith. True evangelical faith is a simple trust that is given to men by God alone.
