Is one who deliberately errs in reciting the Holy Qur’an an infidel, or is it stipulated that he believes in the correctness of what he recited?

Intentionally making a grammatical error (laḥn) in the Book of Allah is a grave sin, but it is not disbelief (kufr) in itself. Rather, disbelief occurs when the intentional grammatical error alters the meaning, coupled with the intention of mockery or stubbornness, or deeming it permissible, or believing in its altered meaning.