Does the Bible contain secret codes?

My bus ride to and from work is about 30-45 minutes each way, during which I sometimes doze off and sometimes read the Bible. Came across the following verse the other day as the bus rumbled down the transitway past the Tunney's Pasture office complex:

The secret things belong to the LORD our God, but the things revealed belong to us and to our children forever, that we may follow all the words of this law. [Deuteronomy 29:29]

Now, some people contend that there is esoteric information embedded in the Bible. The theory is that you perform some sort of calculations ("Gematria," in the Kabbalah tradition) on the text, yielding special hidden information not otherwise accessible. But it seems to me that Deuteronomy 29:29 nixes this idea of hidden information. To wit:

There would seem to be two categories of information referred to in the Scriptures: the secret things and the things revealed. The things revealed "belong to us and to our children forever." Their explicit purpose is to lead us to live according to God's rules. The term forever is significant for two reasons. One, because it's prophetic: here we are talking about it thirty-three centuries later, and the Bible is not going away any time soon. Second and more importantly, because this category of information is put in the special zone of Fundamental Universal Truth --- things that will never change, basic knowledge that underlies all human experiences ("that we may follow the words of this Law," i.e., that we may order our lives as God wants) for all people ("us and our children forever").
The secret things, in contrast, belong to God. The things revealed are ours forever, and so a second contrast is hiding below the surface: the secret things likewise belong to God forever. Never to be divulged. They are His and His alone.

So "gematria," and any similar scheme for ferreting out hidden information from the Bible, can't be for real. The secret things belong to God, forever; and the things revealed belong to us forever, and provide us with all we need to follow Him. There is no third category of knowledge, no "things that we secret for a while until we dug them out;" and there is no overlap between these two.

Does the Scripture provide us with everything required to follow God?

All Scripture is God-breathed and is useful for teaching, rebuking, correcting and training in righteousness, so that the man of God may be thoroughly equipped for every good work. [2 Timothy 3:16-17]

Do we need special esoteric knowledge in addition to that?

At that time Jesus, full of joy through the Holy Spirit, said, "I praise you, Father, Lord of heaven and earth, because you have hidden these things from the wise and learned, and revealed them to little children. Yes, Father, for this was your good pleasure." [Luke 10:21]

I'm guessing that if "little children" can master the requirements, there can't be anything too esoteric about it ...