Is a person who knows some of God’s Most Beautiful Names and Attributes, and is able to learn the rest but has fallen short in doing so, considered a disbeliever?

The names and attributes of Allah are not confined to a specific number. The hadith (prophetic tradition), "Indeed, Allah has ninety-nine names; whoever enumerates them will enter Paradise," means that whoever enumerates these names will enter Paradise, not that Allah has only ninety-nine names. It has been reported in a hadith: "I ask You by every name belonging to You with which You have named Yourself, or revealed in Your Book, or taught to any of Your creation, or kept exclusively in Your knowledge of the unseen." And the Prophet, peace and blessings be upon him, said: "I cannot enumerate Your praise; You are as You have praised Yourself."

The obligatory amount of knowledge to learn about Allah is the general understanding that He has no partner in His Lordship (Rububiyyah), Divinity (Uluhiyyah), names, and attributes. Deficiency in this obligatory knowledge does not necessitate disbelief.