This is from the Summa:
There are two ways in which blasphemy may occur unawares and without deliberation. On the first way, by a man failing to advert to the blasphemous nature of his words, and this may happen through his being moved suddenly by passion so as to break out into words suggested by his imagination, without heeding to the meaning of those words: this is a venial sin, and is not a blasphemy properly so called. On the second way, by adverting to the meaning of his words, and to their blasphemous nature: in which case he is not excused from mortal sin, even as neither is he who, in a sudden movement of anger, kills one who is sitting beside him.
It seems to imply that you don’t need deliberate consent here to sin mortally.
It refers I suppose to spoken blasphemy.
What happens if it is blasphemy of the thought?
For example: Today as I was praying the rosary (I was half asleep) I began to pray the Hail Marys a shorter version of them, then I thought “I have to pray them right” and became a little angry with Virgin Mary because of that, it was a passing thought and I was half asleep. I considered later I may have incurred in blasphemy. There was a little consent for a brief moment but the thought was dismissed right after I knew what I was doing. Now according to Aquinas you don’t need deliberate consent. Nevertheless he says you need to be aware of the blasphemous nature of the thought. Wich I wasn’t at first.
On the contrary according to the Catholic Dictionary entry on Blasphemy:
Speaking against God in a contemptuous, scornful, or abusive manner. Included under blasphemy are offenses committed by thought, word, or action. Serious contemptuous ridicule of the saints, sacred objects, or of persons consecrated to God is also blasphemous because God is indirectly attacked. Blasphemy is a grave violation of charity toward God. Its gravity may be judged by the capital punishment on the Old Testament, severe penalties of the Church, and in many cases also of the State for blasphemous speech or conduct. In order for a person to sin gravely in this manner, he must use blasphemous expressions and ** realize the contemptuous meaning ** of what he says or does. (Etym. Latin blasphemia,blasphemy; from greek blasph_mein, to speak ill of.)
you need to realize the contemptuous meaning of it. I think it is different than realizing the blasphemous nature of it. Because I realized that I was being contemptuous but not realized I was being blasphemous. For example if you blaspheme against a saint not thinking he is a saint, you are aware of the contemptuous but not the blasphemous.
I don’t know if I explained myself correctly. Mainly because English is not my first language. Anyway, do you think mine was a blasphemy?
Thank you.

One* always* has to have deliberate consent (complete consent) in order to commit a mortal sin.

For simplicity sake and language sake - steer more by the Catholic Dictionary.

Compendium issued by Pope Benedict XVI

  1. When does one commit a mortal sin?

One commits a mortal sin when there are simultaneously present: grave matter, full knowledge, and deliberate consent. This sin destroys charity in us, deprives us of sanctifying grace, and, if unrepented, leads us to the eternal death of hell. It can be forgiven in the ordinary way by means of the sacraments of Baptism and of Penance or Reconciliation.

  1. When does one commit a venial sin?

One commits a venial sin, which is essentially different from a mortal sin, when the matter involved is less serious or, even if it is grave, when full knowledge or complete consent are absent. Venial sin does not break the covenant with God but it weakens charity and manifests a disordered affection for created goods. It impedes the progress of a soul in the exercise of the virtues and in the practice of moral good. It merits temporal punishment which purifies.

Or pick your native language here (hope it is there) and find the same article number:

(second one)

Some things to consider in your examine:

Thanks, Bookcat. I was confused by the two texts, but I guess it was without full knowledge after all.

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