Is it normal that i am annoyed by my family thanking god?

Clementia?

In Roman mythology, Clementia was the goddess of forgiveness and mercy. She was deified as a celebrated virtue of Julius Caesar, who was famed for his forbearance, especially following Caesar's civil war with Pompey from 49 BC. In 44 BC, a temple was consecrated to her by the Roman Senate, possibly at Caesar's instigation as Caesar was keen to demonstrate that he had this virtue. In a letter to his friend Atticus, Cicero is discussing Caesar's clementia: "You will say they are frightened. I dare say they are, but I'll be bound they're more frightened of Pompey than of Caesar. They are delighted with his artful clemency and fear the other's wrath." Again in Pro rege Deiotaro (For King Deiotarus) Cicero discusses Caesar's virtue of clementia. "Yes, you, Gaius Caesar, are the only conqueror in whose hour of triumph none save combatants have fallen. We, free men born in freedom's fairest clime, so far from finding you a tyrant, have seen in you a leader of unbounded mercy in the day of victory" (34.1). There is not much information surrounding Clementia's cult; it would seem that she was merely an abstraction of a particular virtue, one that was revered in conjunction with revering Caesar and the Roman state. Clementia was seen as a good trait within a leader, it also the Latin word for "humanity" or "forbearance". This is opposed to Saevitia which was savagery and bloodshed. Yet, she was the Roman counterpart of Eleos the Greek goddess of mercy and forgiveness who had a shrine in Athens. In traditional imagery, she is depicted holding a branch and a scepter, and may be leaning on a column.

My priorities include logic and truth. Theirs include giving thanks to a mythical diety.

i think he can live without be entirely focused on his sister's cancer

Yes. I told them it was illogical and they told me I was being insensitive. I guess logic is insensitive.

Ash Shakur?

Ash Shakur is translated into "The Appreciative". In his book, "Al-Maqsad Al-Asna fi Sharah Asma' Allahu al-Husna" (aka The best means in explaining Allah's Beautiful Names), Imam Al Ghazali translates Ash Shakur as "The One Who Expresses Thankfulness by rewarding bounteously". He goes on to say that Ash Shakur is "the One Who rewards trivial pious deeds with many grades, and the one who gives unlimited happiness in the life to come for activity during a limited period (in this life). The one who rewards the good deed with multiples of it is said to be thankful for that good deed, and the one who praises the performer of this good deed is also said to be thankful for it. If you consider multiple rewards (to be the criterion in this matter), then there can be no absolute Ash Shakur except God Most High, because His increase of the reward is not restricted and limited since the blessings of Paradise are infinite."

Incorrect.

I once thought much like you, however I have since learned that I also was incorrect.
There is actually some truth in what they believe in.

Momos?

Momus or Momos (μῶμος) was in Greek mythology the personification of satire, mockery, censure; a god of writers and poets; a spirit of evil-spirited blame and unfair criticism. His name is related to μομφή, meaning 'blame' or 'censure'. He is depicted in classical art as lifting a mask from his face.