In December 1545, the First Session began and lasted until March of 1547. But as soon as they established the Council, fighting broke out again over what to call it.

The Second Session, which lasted from May 1, 1551, until April 28, 1552, was where the Council actually finalized all of the decisions discussed during the period outside of Trent in the four years previous.

The Third Session was held on February 4, 1546. The decisions were as follows:

1. A decree concerning the symbol of faith and matters of faith and morals. Tradition and Scripture were both upheld as valid sources of divine revelation.
2. A decision that the Vulgate is the authentic text. This decision meant rejecting the Received Text, upon which the King James Version is based.

In the Fourth Session on May 24, 1546, deliberations about nature and consequences of original sin ended in the decision that original sin is cancelled by baptism.

Also at this council a Decree Concerning the Canonical Scriptures asserted that "anyone who dared study Scriptures on their own must 'be punished with the penalties by law established.' The Council of Trent went so far as to forbid even the printing of and sale of the Bible. Anyone daring to violate this decree was anathematized, or cursed and damned to Hell for it.”ⁱ

What is not generally known is that the Bible had previously been placed on the Index of Forbidden Books list by the Council of Toulouse/Toledo in 1229. It remained in the index until it was discontinued and replaced at Vatican Council II. “Anyone reading or owning a 'forbidden' book was anathematized, or cursed and remanded to hell for doing so.”ⁱⁱ

Cannon 14 from the Council of Toulouse says that the Roman Catholic Church: Forbids the laity to have in their possession any copy of the books of the Old and New Testament...and most strictly forbids these works in the vulgar tongue.ⁱⁱⁱ

The Fifth Session, June 17, 1546, brought about the following decisions:

1. A decree concerning original sin. Original sin is the sin that Adam committed in disobeying the commandment of God. As a consequence of this first sin, they lost the grace of original holiness and received a hereditary stain with which we are born on account of our origin or descent from Adam.
2. Five anathemas regarding belief on original sin. If one did not adhere to the above dogma, they would be anathema from the Church.
3. The first decree on reform. This decree included The Establishment of Lectureships in Holy Scripture and the Liberal Arts, and Preachers of the Word of God and Questions of Alms

Between the fifth and sixth sessions there was a war between Charles V and the Protestant Princes.

The Sixth Session, held on January 13, 1547, resulted in a decree concerning justification in 33 canons.

Since there is being disseminated at this time, not without the loss of many souls and grievous detriment to the unity of the Church, a certain erroneous doctrine concerning justification, the holy, ecumenical and general Council of Trent...strictly forbids that anyone henceforth presume to believe, preach or teach otherwise than is defined and declared in the present decree. ^iv

The Seventh Session, on March 3, 1547, brought about these decisions:

1. A decree concerning the Sacraments in general (affecting 13 canons), 14 canons concerning baptism, and 3 canons dealing with confirmation. The canons on the Sacraments in general were essentially trying to discourage anyone from doubting the authority of the recently instigated New Laws, and attempting to justify the changes by claiming God Himself was behind all the reform. The canons on title="Read about the Biblical stance on baptism">baptism also contained many references to the Churches authority and threats of anathema. The 3 canons on confirmation appealed to the authority of the Church and were just as unBiblical as the previous canons in their claims.

2. A decree in 15 chapters concerning reform—the Holy Council intended to continue the work begun concerning residence and reform. They thought it well to decree these reforms by the authority of the Holy See.

An infectious disease broke out in Trent and was killing the members of the council, so the cardinal legates proposed a transfer for the Eighth Session to Bologna. Charles V opposed the change and refused to recognize it, so the Eighth, Ninth and Tenth Sessions were incomplete except for decrees concerning translation, prorogation, and a bull of resumption of the Council of Trent under Julius III. After the Pope died, the Council moved back to Trent in order to placate the emperor.^v

During the Eleventh Session, held on May 1, 1551, the dogma on the Sacrament of the Eucharist was composed.

The Twelfth Session, however, was essentially cancelled because the French king prohibited his delegates from attending.

The Thirteenth Session on October 11, 1551, included these decisions:

1. A decree concerning the sacrament of the Eucharist in 8 chapters and 11 canons; these solidified proposed dogma from the short Eleventh Session.
2. A decree concerning reform; these related to the authority of Bishops in regard to criminal laws.
3. A decree to postponing the definition of four articles concerning the Eucharist.
4. A decision to grant letters of safe conduct for Protestants attending the next Council.

The Fourteenth Session, November 25, 1551, upheld the following decisions:

1. A canonical decree on the Sacrament of Penance.

The manner in which this sacrament is done has developed over time, but the basics have always remained:

Confession: You must confess all known mortal sins to a priest. You can confess all your sins, but start with any mortal sins. The priest is bound by the most absolute secrecy and confidentiality known to humankind. Not even the Pope can get a priest to tell who went to him for confession or what was confessed. The priest must be willing to endure prison, torture, and death before violating the Seal of Confession, the secrecy of the sacrament.

Contrition: You must be sorry you committed the sins and resolve to do your best not to repeat them.

Penance: After you confess your sins, the priest gives you a penance to perform. A penance may be to do something nice for your enemy every day for a week. It may be to visit a nursing home or hospital one day a week for a month. It may be to donate time to a soup kitchen or clothing bank. It may involve any one of the corporal or spiritual works of mercy. Or it may be a set of prayers, such as saying the "Our Father" or the "Hail Mary" a certain number of times. Whatever the penance, it’s merely a token, because Catholics believe that the sacrifice of Christ on the cross is what made atonement for our sins. Your penance is for your benefit—to remind you that God comes first and you come last.

Absolution: The priest or bishop hearing your confession (deacons don’t have the power to celebrate this sacrament), offers forgiveness, saying a prayer that calls on God to give you absolution and peace.”^vi

2. Three chapters changed in the canons concerning the Sacrament of Extreme Unction. “The Sacrament "Extreme Unction," also called "Last Rites" or "Anointing of the Sick," is the anointing given to those who are gravely bodily ill, especially those in danger of death from bodily illness or from violence already done to the body"^vii

3. Fifteen canons condemning heresies to do with different beliefs about penance.

4. Canons condemning heresies on wrong uses of Extreme Unction.

The Fifteenth Session was held on January 25, 1552, and was very brief. The actions of this Fifteenth Session included another safe conduct promise for Protestants.

Newly inducted Protestants who were starting to acquaint themselves with the Council demanded that all earlier decisions of the Council be recalled and that all debates be deferred. The Council did not accept these demands. They were discussing the Holy Sacrifice of the Mass and the ordination of priests, but deferred these discussions to the Pope in order to give the Protestants safe conduct.

Around this time, the attack of Maurice of Saxony on Charles V made the city of Trent unsafe for the council, so the Sixteenth Session of April 23, 1552, was forced to produce a decree suspending the Council for two years because of traveling dangers.

Shortly after these events, the Pope died. Pope Paul IV (1555-1559), who was hastily elected, agreed to the proposed reforms to the Catholic Church but did not reconvene the Council. His successor, Pope Pius V (1559-1565), reconvened the Council, but the problem of a new location was an immediate issue. Spain’s emperor Ferdinand and the King of France opposed going back to Trent. The Protestants opposed the Council itself because they knew it would cause many restrictions. After a few altercations, the different countries involved left the decision to the Pope, but the Protestants still argued against the Council.

The Seventeenth Session was ordered to begin on Easter, 1561, in Trent. However, the delegates were not able to arrive on time and it was postponed until January 18, 1562. This session was taken up with arguments against the Council by the Protestants.

The Eighteenth Session on February 25, 1562, included these decisions:

1. A decree concerning the choice of books (opinions on this were included in the Index of Forbidden Books).

”Some notable authors and intellectuals whose works are widely read today in leading universities worldwide and are now considered as the foundations of science were listed on the Index. E.g. Kepler's New Astronomy and World Harmony were quickly placed on the Index after their publication.^viii”

2. The granting of safe conduct to the German nation in a general congregation and, an extension to other nations.

The Ninteenth and Twentieth Sessions were unproductive again because of Protestants’ arguments against the Council.

The Twenty-First Session on July 16, 1562, upheld the following decisions:

1. A decree concerning Communion.
2. A decree on Communion of little children.
3. A decree on reform concerning ordination to the priesthood.

The Twenty-Second Session, September 17, 1562, produced the following:

1. A decree on the sacrifice of the Mass.
2. A decree on the suppression of abuses in offering the sacrifice of the Mass.
3. A decree concerning various morals of the clergy.
4. A decree on the Eucharist.

The Twenty-Third Session, July 15, 1563, concluded with a decree on the Sacrament of Holy Orders and a decree concerning marriage including marital contracts, spiritual relationships, public honesty, fornication, situations wherein marriage is prohibited, punishments for abductors, marriage of vagrants, punishment for concubinage, retaining liberty of marriage, and suspension of marital ceremony on certain Holy dates.

The Twenty-Fourth Session’s decisions on November 11, 1563, included the following:

1. A decree in 12 canons on the doctrine of the Sacrament of Matrimony; particularly to define the institute and then to declare those who disbelieve the stated law to be anathema.
2. A decree on the creation of Bishops and Cardinals and other such related decrees on the religious personnel in the Church.

The Twenty-fifth and Final Session, held December 3, 1563, finished with the following eight decisions:

1. A decree on the veneration and invocation of the saints, their relics, and images, and purgatory.
2. A decree concerning reform of monks and nuns.
3. A decree concerning living conditions, authority limits, and duties of cardinals and bishops.
4. A decree upholding chastity among the religious.
5. A decree on indulgences.
6. A decree on fasting and feasting days.
7. A decree that the Pope prepares the Missal, the Breviary, and the Catechism.
8. A list of forbidden books.

This included the blacklisting of some Protestant scholars even when writing on subjects a modern reader would consider outside the realm of dogma. Unless they obtained a dispensation, obedient Catholic thinkers were denied access to the botanist Conrad Gesner's Historiae animalium or the botanical works of Otto Brunfels, those of the medical scholar Janus Cornarius, to Christoph Hegendorff or Johann Oldendorp on the theory of law, Protestant geographers and cosmographers like Jacob Ziegler or Sebastian Münster, as well as anything by Protestant theologians like Martin Luther, John Calvin or Philipp Melancthon. The result from the entire Council of Trent forbidden books policies resulted in the Tridentine Index—which contains over 600 books—remained the basis of all later lists until the Index Leonainus published in 1897. Certain versions of the Bible were prohibited from both of these indexes.”^ix