Systematic Theology (ST) is the systematic study of the major subjects in Scripture—God, man, Christ, salvation, church, and last things. (The more formal names for these subjects are theology proper, anthropology, Christology, soteriology, ecclesiology, and eschatology.) A teacher of ST must therefore be a master of the Bible. But this way of studying theology is beneficial to Christians, as it helps them understand the Bible as a whole.
Systematic Theology asks, “What does the Bible as a whole say about _______ ?” Take the subject of sin for example. It began with Adam and Eve (Genesis 3), it has corrupted the entire human race (Romans 1), and it is forgiven and remedied through the work of Christ and His Spirit (Ephesians 2 and 5).
As far as curriculum goes, it is best to have students first take a Bible survey course. After a student has a good understanding of the books and the overall story of the Bible, then he or she can move on to ST. A school that has a one-year Bible survey course in the 9th grade can follow up with ST in the 10th grade (or 11th grade if Bible is split into two years). Though ST can be studied in one semester, students will certainly benefit from an entire year of this subject.
The Best Systematic Theology for High School
There are many ST books to choose from for the college and seminary level. But the best ST book for high school is Bible Doctrine by Wayne Grudem. This is a condensed version of Grudem’s Systematic Theology. The advantages of Bible Doctrine are: (1) it has shorter chapters; (2) it has good chapter content questions for assignments; and (3) it is easier for students to carry around because of its size.
Grudem’s theology is strongly Protestant with Reformed leanings. He is a five-point Calvinist and adheres to covenant theology (rather than dispensationalism). But he does not fit neatly in the Presbyterian and Reformed camp, for he is also credobaptist, charismatic, and premillennial. This will be pleasing to some and displeasing to others. But Grudem gets his major doctrines right, and a teacher can counter Grudem’s arguments where he disagrees. This is not a perfect book, but it is the best available systematic theology book for high schoolers.
Others Systematic Works
John Frame has also written a great short systematic theology called Salvation Belongs to the Lord. Though the format is not as good for coursework, this is still an excellent read. Frame's theology is more Reformed than Grudem's. There are other great systematic theology works out there, including Berkhof, Bavink, and Frame's longer work. But it is hard to see these working well for high school students. They are more suitable for college, seminary, and self-study.