If you studied a foreign language in high school or college, one of the more difficult facets of learning a new language is learning a new way of thinking. Language and thinking are both like the potter, and they are both like the clay. They mold each other.
Theological language is no different. Most of the time, you and I don't create new theological terms (and we should weary of those who do). We inherit them. And when we inherit language, we are also inheriting the process of thinking by which those new terms were deemed necessary.
Another issue with language is that it eventually becomes jargon. Encyclopedias are packed into a single word. As more and more books are written on a topic, more and more ideas are packed into a single word. Words inherit baggage in like way we inherit the words. The further we're detached from the world of words, the harder it is to be familiar with the jargon.
So what I want to do is bring up some classic theological language and explain the ideas behind the words. This will help all of us be more familiar with the way not just theologians speak but the way the Bible speaks, and therefore, the way God speaks.
The Bible is a big book. If we don't have ways of quickly summing up what it says, we'll never get anywhere. And jargon, or theological language, is the way that happens.
We won't necessarily go in alphabetical order since ideas don't come in alphabetical order. Besides, some words are just more important than the others.
So let's start with a good one.
COVENANT: noun; a relationship initiated by God including binding obligations between two parties; is the primary way God moves salvation history forward.
The Bible speaks of creating covenants in two ways: to "cut" a covenant and to "establish" a covenant. To "cut" a covenant is to begin the covenant. To "establish" a covenant is to essentially renew it or recommit to your side of the covenant's obligations.
Sometimes, you might hear of a covenant being "unilateral" or "bilateral." That just means that either one party has all the obligations (unilateral) or both parties have obligations (bilateral). The truth is more complex than that. All of the covenants have obligations for both parties. The real difference is really if the particular covenant has a termination date.
The Bible is full of covenants. There is a covenant made between God and Adam and Eve (even though the word isn't used in the story, all the marks of a covenant are there: binding obligations on both parties). If Adam and Eve are faithful, they will inherit eternal life. One side of the covenant fails (start looking for a theme there), and the covenant is broken. Adam and Eve are removed from the land God had given them and will die a physical death. But before being dismissed from their home, God promises that there will one day come a child way down the line who will undo what they did.
Then, there is a covenant between God and Noah. After purging the earth of most of its sinners through a worldwide flood, God promises not to do so again. The world will be destroyed again one day, but there will be less water. Even this covenant, marked by the rainbow, has obligations for both parties: God will not destroy the earth by water, and mankind will not eat meat while still on the animal. This must have a been a bone of contention in Noah's day. Some parts of the world still do this: carve meat off of a living animal. So we can eat meat, but we cannot be cruel to animals.
Then, of course, there is the covenant with Abraham. Some have argued that there are multiple covenants with Abraham. But really, it's all one, even though components of it are added throughout Genesis 12 through 17. In the Abrahamic covenant, God promises to bless the whole world through Abraham's family. Specifically, this covenant is actually a partial fulfillment of the promise God made to Adam and Eve that one of their far-off children would fix everything.
The Mosaic covenant is made at Sinai, and it involves the giving of the law (or better, instruction) to the people who are themselves a partial fulfillment of the Abrahamic covenant, that a nation would be made up of Abraham's children (do you see all the interconnectedness yet?). When the people obey the instruction, all goes well and they show the world how God acts in righteousness. When they disobey the instruction, all goes poorly and they show the world how God acts in righteousness.
The Davidic covenant is made specifically with the family line of David (who is a subset of Israel, who is a subset of Abraham). The kings will be the official keepers of the law and will be responsible for the people's faithfulness to the law. Part of this covenant is that there will always be a king in David's family line on the throne, as long as the nation is obedient. One day, a king of David's line will rule forever and the people will never again rebel against God.
The Old Testament promises a new covenant in the future when God promises to do just that: to remove all sin from the community of righteousness. There will be a king from David's line who rules the people of God forever. The new people of God will not be a mixed people, where you are considered an Israelite just because you were born an Israelite. The new people of God will be born twice: once physically and once spiritually.
The new covenant was instituted by Christ at his death and resurrection. Now, all those who are in Christ are the true Israel because Christ is the true Israel. In the new covenant, all of God's promises made in the previous covenants are fulfilled in Christ. Many, if not most, of them are inaugurated, meaning they have been proven but not yet finalized. That is yet future, when Christ returns a second and final time.
God works through covenants, and that is the primary way of reading Scripture.