The ruling on one who is ignorant of the pillars and conditions of prayer: Is he excused for his ignorance?

Question:
Adam Muhammad says: If a person is ignorant of matters of worship, particularly matters of prayer, is he held accountable and does he sin? And is his prayer invalid?

Answer:
Yes, he is held accountable, and his prayer may not be valid if it is based on ignorance of its pillars, its conditions, its pillars, and its obligations. It is obligatory for the Muslim to learn the matters of his religion. This is from the necessary knowledge for which no one is excused; no one is excused for neglecting it.
Every Muslim is required to have this type of knowledge, which is what straightens his religion: his creed, his prayer, his fasting, his zakah, and his Hajj. No one is excused for being ignorant of this. It is necessary to learn it and to act upon it and to perform these obligations, which are the pillars of Islam and its obligatory duties, so that a person does not let his religion be lost. And this is easy, and praise be to Allah. He should ask the people of knowledge, and he should learn. Praise be to Allah, the curricula are all built upon this; they are all filled with this. The stages of study, from the beginning to the end, proceed with this and with this religion and its rulings. So praise be to Allah. The Muslims' education is based on the Book and the Sunnah, and on giving advice and spreading good among the people. Yes.