How well do you know the Lord? It is not a very difficult question when you think about it. We all have a certain knowledge of God implanted in our very soul, but that is not the knowledge I am speaking of here (everyone, even atheists, know that God exists). I am asking about the more personal knowledge. Not everyone has that deeper knowledge of God. Yet, without it, no one will go to Heaven.
Our entire lives are spent in God's creation, and everything in creation speaks about God (Scripture tells us this in many places). Thus, it is impossible to be without knowledge of God unless we choose to ignore it or cover it up (and vast numbers of people today do that--even some Catholics!).
When the Church tells us that we need to have knowledge of God it certainly is referring to the basic doctrinal knowledge (for example: God is not an alien from another planet, nor is He a non-trinitarian monad), but it goes beyond that. The Church wants all of us to learn Who God is in our inner soul. We are expected to open our hearts to Him, and come to know Him in ways that are not able to be defined on paper.
This is not a subjective knowledge of God, because it must be in full accord with the doctrinal knowledge that we have. Remember, God cannot have a contradiction in His being; He is Who He is, and that is unchangeable. This non-subjective knowledge of God is a personal knowledge. It is comparable to a husband and wife that know each other's inner person in a way that the rest of the world cannot know.
It is this knowledge that you must be working on. Seek it, strive for it, and do not compromise on it. It is easy to read a book about God, but it is an entirely other thing to come to find that personal knowledge. It does not show up in an instant; it takes a long time of actively engaging in the things of God to get used to what He is like (but it is possible). This is why the Church gives us spiritual disciplines: precisely so that in doing them, we will come to know God.