Here is a link to the Catholic Encyclopedia, perhaps the section on the decrees of Trent are more clear in this article.
The negative document we call the canons on baptism decreed by the Council of Trent (Sess. VII, De Baptismo), in which the following doctrines are anathematized (declared heretical):
*]The baptism of John (the Precursor) had the same efficacy as the baptism of Christ,
*]True and natural water is not necessary for baptism, and therefore the words of Our Lord Jesus Christ “Unless a man be born again of water and the Holy Ghost” are metaphorical.
*]The true doctrine of the sacrament of baptism is not taught by the Roman Church,
*]Baptism given by heretics in the name of the Father and of the Son and of the Holy Ghost with the intention of performing what the Church performs, is not true baptism,
*]Baptism is free, that is, not necessary for salvation.
*]A baptized person, even if he wishes it, can not lose grace, no matter how much he sins, unless he refuses to believe.
*]Those who are baptized are obliged only to have faith, but not to observe the whole law of Christ.
*]Baptized persons are not obliged to observe all the precepts of the Church, written and traditional, unless of their own accord they wish to submit to them.
*]All vows made after baptism are void by reason of the promises made in baptism itself; because by these vows injury is done to the faith which has been professed in baptism and to the sacrament itself.
*]All sins committed after baptism are either forgiven or rendered venial by the sole remembrance and faith of the baptism that has been received.
*]Baptism although truly and properly administered, must be repeated in the case of a person who has denied the faith of Christ before infidels and has been brought again to repentance.
*]No one is to be baptized except at the age at which Christ was baptized or at the moment of death.
*]Infants, not being able to make an act of faith, are not to be reckoned among the faithful after their baptism, and therefore when they come to the age of discretion they are to be rebaptized; or it is better to omit their baptism entirely than to baptize them as believing on the sole faith of the Church, when they themselves can not make a proper act of faith.
*]Those baptized as infants are to be asked when they have grown up, whether they wish to ratify what their sponsors had promised for them at their baptism, and if they reply that they do not wish to do so, they are to be left to their own will in the matter and not to be forced by penalties to lead a Christian life, except to be deprived of the reception of the Eucharist and of the other sacraments, until they reform.
The doctrines here condemned by the Council of Trent, are those of various leaders among the early reformers. The contradictory of all these statements is to be held as the dogmatic teaching of the Church.