Reasons for systematic theology? Let me briefly mention six.
Reason 1: The Bible’s interest in truth demands it.
Systematic theology is nothing if it not the pursuit of truth, and truth
is essential to biblical Christianity. Jesus said the truth will set
you free (John 8:32). The Holy Spirit is called the Spirit of truth (John 14:17). The work of the Holy Spirit was to guide the apostles into all truth (John 16:13). Eternal life is to know the only true God (John 17:3). Jesus prayed that we would be sanctified in the truth (John 17:17). Paul warned that for those who do not obey the truth there will be wrath and fury (Rom. 2:8). We are to be transformed by understanding the truth (Rom. 12:2). People can go to hell for preaching what is not true (Gal. 1:8).
People within the church should be corrected when they believe the
wrong things. “[An elder] must hold firmly to the trustworthy message as
it has been taught, so that he can encourage others by sound doctrine
and refute those who oppose it” (Titus 1:9). People are sometimes to be kept out of your house for believing what is not true (2 John 9-10). The wicked perish because they refused to love the truth (2 Thess. 2:10). The workman of God must rightly handle the word of truth (2 Tim. 2:15).
In other words, no Christian worthy of the name should be indifferent
to the pursuit of right doctrine. As Louis Berkhof put it, “They who
minimize the significance of the truth, and therefore ignore and neglect
it, will finally come to the discovery that they have very little
Christianity left” (Systematic Theology, 29).
