Although I know, as the Fathers show, that infants have been baptized occasionally from the earliest times, still it was not so universal a custom as it is now, but the common practice was as soon as they arrived at the age of reason to form them into classes for instruction in the Word of Salvation (hence they were called catechumens, i.e., persons under instruction). And after a firm faith had been implanted in their hearts and they had confessed the same with their mouth, then they were baptized. I could wish that this custom of giving instruction were revived to-day, viz., since the children are baptized so young their religious instruction might begin as soon as they come to sufficient understanding. Otherwise they suffer a great and ruinous disadvantage if they are not as well religiously instructed after baptism as the children of the ancients were before baptism, as sermons to them still prove. (Huldreich Zwingli, Ausleqen und Begrundung der Schlussreden oder Artikel, as found in Huldreich Zwingli's Werke, Vol. 1, pp. 239-240, quoted by Jackson, Huldreich Zwingli, p. 243)Some of Zwingli's followers became anabaptists and used some of Zwingli's writings in support of their position. On August 31, 1526, Zwingli wrote:
Then the blind fellow adduced what I had written about teaching catechumens some years ago in the book on the Sixty-seven Articles. For he did not know that it was our custom that boys also as in former times be taught the rudiments of the faith. This he referred to baptism, rather indiscreetly; as if I had said that it was my counsel that the custom of not baptizing infants be brought back again, when I had spoken of imbuing children in the elements of faith. When he saw that he had erred in this matter he was charming.(Huldreich Zwingli, Letter to Peter Gynoraeus, August 31,1526, as found in Huldreich Zwingli's Werke, Vol. 7, p. 534. quoted in Jackson, Huldreich Zwingli, p. 253)Zwingli does not say that infant baptism is invalid in the 1524 quote. But he pretty clearly says that he thinks it's better to wait until the child is older. His position is similar to some statements made by Tertullian although Tertullian believed in baptismal regeneration which Zwingli rejected. However, rather than saying that he was wrong in what he had previously written Zwingli tries to pretend that the other guy just didn't understand. Zwingli was a politician and this becomes apparent on more than a couple occasions. The anabaptists had studied under Zwingli and received their foundational teachings from Zwingli. They understandably felt betrayed when Zwingli turned on them. In conversations with the anabaptists, Zwingli told them that he didn't think the theological differences between them and him were significant enough to divide over but he did not always say this same thing to the state. At times he would call for leniency, at other times he would call upon the state to get rid of these anabaptists. Some have wondered if Zwingli actually changed his position on infant baptism or if he decided to start defending infant baptism for political reasons. I don't think we can know for sure, but we do see a general pattern throughout Zwingli's career where he seems to change theological positions when it is politically advantageous.
When Zwingli wrote his defense of infant baptism, he said that he didn't believe that anyone else had ever defended infant baptism with the arguments he was making (Yoder, Tdufertum und Reformation, p. 18.). Historically the church has defended infant baptism based on the command to disciple all nations by baptizing them (since infants are part of the nations) and also on the belief that infants are born sinners. But Zwingli denied the doctrine of original sin. He wrote:
Whether we wish it or not, we are compelled to admit that original sin, as it is in the descendants of Adam, is not properly sin, as has already been explained, for it is not a transgression of the Law. It is therefore properly a disease and a condition.Zwingli's denial of original sin led him to defend infant baptism on covenantal grounds. Zwingli argued that infant baptism replaced circumcision and so the children of believers should be baptized just as the male children of believers were circumcised under the old covenant. The Calvinist churches have followed Zwingli in this argument.
But Zwingli's character and general approach is most apparent in his debate with Luther and the events that followed. Hermann Sasse's excellent book, This is My Body, provides a very helpful reconstruction of the debate. Throughout the debate, Luther clung tightly the Scriptures and Zwingli objected on philosophical grounds. They wrote up a statement in which they stated fourteen points of agreement and one point of disagreement. But after the debate, Zwingli published his own edition of the proceedings of the debate and the resulting articles. In his edition Zwingli bragged about how he supposedly beat Luther in debate and included added "explanations" to the articles in the margins that basically denied the very things that the articles of agreement said. Luther understood the articles to be a real confession of faith to die for. Zwingli understood them to be a political statement that could be read in various ways to bring people of different beliefs together to co-operate politically.
Zwingli's method of Biblical interpretation was rationalistic. Even though the average person would probably put Zwingli and the Roman Catholic church on opposite ends of the spectrum on the issue of the Lord's Supper, the underlying presuppositions are almost identical. Throughout the debate, Zwingli quoted Thomas Aquinas who taught that revelation can never contradict reason. Aquinas used this in support of transubstantiation. Zwingli used this in support of his purely symbolic view of the Supper. Luther took the exact opposite position and said that revelation often contradicts human reason. In many ways liberal Bible scholars can find their spiritual father in Zwingli. If reason tells us that if it looks like ordinary bread and wine it must be ordinary bread and wine, then reason also tells us that people don't rise from the dead, walk on water, or do any of the other things that the Scriptures say.
In addition to Zwingli's rationalistic doubt of the plain words of Scripture, when he was certain that he was right but unable to find Scriptural support he would sometimes appeal to visions:
We began, therefore, to think over the whole, revolve the whole; still the examples which occurred were the same I had used in the Commentary (on True and False Religion), or of the same kind. I am about to narrate a fact--a fact of such a kind that I would wish to conceal it, but conscience compels me to pour forth what the Lord has imparted, though I know to what reproach and ridicule I am about to expose myself. On the thirteenth of April I seemed to myself, in a dream, to contend with an adversary, a writer, and to have lost my power of speech, so that what I knew to be true my tongue failed me in the effort to speak...Though, as concerns ourselves, it be no more than a dream we are telling, yet it is no light thing that we were taught by a dream, thanks be to God, to whose glory also we are telling these things. We seemed to be greatly disturbed. At this point, from a machine," (the theatrical apparatus by which supernatural persons were made to appear in the air,) “an adviser was present (whether he was black or white I do not at all remember; for it is a dream I am telling), who said: You weakling! answer him that in Exod. xii. 11, it is written: 'It is the Phase--that is, the Passing over of the Lord.' On the instant that this apparition showed itself I sprung from my couch. I first examined the passage thoroughly in the Septuagint, and preached upon it before the whole congregation with all my strength. This sermon dispelled the doubts of the students, who had hesitated because of the obstacle of the parable" (that "is" meant "signify" only when a Parable was explained). "Such a Passover of Christ was celebrated on those three days as I never saw, and the number of those, it is thought, who look back to the garlic and flesh-pots of Egypt is going to be far less." (Zwinglii Opera. Turici. 1832. III. 841.)
In this passage, Zwingli attempts to refute the Lutherans who he refers to as those "who look back to the garlic and flesh-pots of Egypt." But the passage he appeals to doesn't help him at all. In Exodus 12:11, Zwingli assumes that "it" means "the Lamb" and the meaning is that the lamb signifies the Passover. But the word "is" is not found in the Hebrew. Also, "it" does not refer to just the lamb but everything that precedes. But even apart from this, Zwingli's appeal to divine revelation to take us away from the plain words of Scripture is disturbing. If Zwingli did in fact see a vision it was inspired by demons or his own sinful nature.
I'm aware that most Calvinists will say that they have some problems with Zwingli as well. But I've noticed that if you attack Zwingli, most Calvinists will take it as an attack on Calvin. There is also a general shift in Calvinist churches away from a Calvinist understanding of the sacraments to a Zwinglian view. At any rate, I think Calvinists and Baptists should at least be aware of who this Zwingli fellow was. He is not a hero of the faith. He is an enemy of the faith. He was a rationalistic Pelagian politician who had more confidence in his own reason than he did in God's Word.
Just as an aside, I know that some in the Calvinist camp think that if only Calvin had made it to the Marburg Colloquy, Lutherans and Calvinists would be united today. But I don't think there is any real reason to believe this. Zwingli's basic arguments against the Lutheran view are essentially the same as Calvin's.
The bread is the body of Christ. The wine is the blood of Christ. They are for the forgiveness of your sins. That's what Jesus says.