فَاعْلَمْ أَنَّ الْإِيمَانَ فِي الشَّرْعِ هُوَ التَّصْدِيقُ بِمَا جَاءَ بِهِ مِنْ عِنْدِ اللَّهِ تَعَالَى
In the religious sense, faith is affirmation of what the Messenger brought from Allah Most High.
The definition has two components: the act of assent and the content assented to. It is not limited to the historical assertion that a prophet existed; it affirms his mission and the divine message he conveyed.
This does not require separately rehearsing every doctrine at all times. General assent establishes the basis, while detailed faith makes particular beliefs explicit.