While Zwingli was for a time of the opinion that it were better to abandon the baptism of infants, he became in the course of a few years, as pointed out elsewhere, one of the foremost opponents of the practice of believers’ baptism. If we inquire into the causes for the change in his position on this question, his own writings give us the information which we desire. Not through the study of the Scriptures was he led to defend infant baptism, but through the acceptance of the opinion that a union of church and state was necessary for the success of the Reformation.
In Zwingli’s view the church needed the strong arm of the state to become firmly established and to overcome all opposition. He was led to realize that some of the citizens of Zurich (possibly a majority) would follow other religious leaders, if the state did not prescribe the Zwinglian creed. Unless an exclusive state-church was established and the acceptance of other creeds made unlawful by the state, the (nominal) unity of the church would be lost. Moreover, it was doubtful whether the state-authorities could be persuaded to consent to the toleration of free churches organized on New Testament principles.
Zwingli decided to go hand in hand with the state in the reformation of the church. He accepted the view that a union of church and state, (and hence infant baptism) was necessary for the prosperity of the church. It is clear from his own testimony that his decision in favor of infant baptism was based primarily on expediency and the supposed needs of the church. J. M. Usteri says correctly: ‘The impulses which led him in this instance were not the results of theological thinking, but had their cause in the [supposed] needs of the church.’
It must not be supposed that I care much for infant baptism. — If I should notice that this practice is not conducive to God’s honor and to a Christian life, I should readily change my opinion.” “If infant baptism had never been practiced, it could be introduced tomorrow, if we would see that it is conducive to peace and to the good [of the church].” “For I know that infant baptism brings to the Christian people great blessing.” “If the matter is closely looked into, it will be seen that ye contend for vain outward things,” he addressed the Swiss Anabaptists who insisted on believers’ baptism. “Should not infant baptism, as well as all other outward things be discreetly used or abandoned, whichever would be most conducive to the prosperity of the Christian church?
The Swiss Anabaptists, on the other hand, pointed out that Zwingli lost sight of the fact that baptism is a command of Christ. Conrad Grebel in his Defense, addressed to the Council of Zurich, writes: “They say it is not of importance how baptism is used, but this opinion can not be established by Scripture, for the Scriptures indicate that it is God’s will that his commandments and rites should be kept as he has commanded them.” And frequently Zwingli himself asserted that error on the point of baptism is a most serious mistake. In his Book on Baptism he defended the opinion that “those who consent to rebaptism, [i. e. the Anabaptists] crucify Christ anew.”