فَالَّذِي يَحْصُلُ لَنَا هُوَ الْإِذْعَانُ وَالْقُبُولُ لِتِلْكَ النِّسْبَةِ
What is acquired is submission to and acceptance of that relation.
Understanding a report's meaning, grasping the relation between subject and predicate, and accepting that relation as true are distinct aspects. Merely forming a conception of a claim is not identical to affirming it.
For example, someone may understand what “the Messenger is truthful” means without accepting it as true. Understanding the words alone therefore does not establish the assent required in faith.