Al-īmān al-ijmālī: general acceptance of the true message of the Messenger ﷺ.
Al-īmān al-tafṣīlī: affirming particular doctrines individually.
General assent connects a person with the truthful divine message. As knowledge develops, that assent becomes articulated in such matters as prayer, fasting, and the Last Day.
Growing in detailed knowledge does not automatically mean there was no essential assent beforehand. Yet deliberately denying a teaching once its decisive meaning and attribution are clear differs from simply not having encountered its details.