The following is an essay I submitted for military chaplain endorsement. There was a page limit, and so much more could have been written on this subject, and indeed much has been written by better sources here, here and here.
Reformed theology focuses on the study of the Triune God, in order that man may rightly glorify Him. Rightly glorifying God is foundational to Reformed theology because that is man’s chief end. Scripture informs us of what man is to believe concerning God and what duty God requires of man. Therefore, scripture is God-centered and not man-centered. In light of this, Reformed theology rightly holds to the inerrancy and infallibility of Scripture. It is the only rule to direct us on how we should glorify God and enjoy Him forever. Reformed theology affirms the Bible’s teaching of its perspicuity, meaning that overall scripture is clear and can be clearly understood by all so that even a child may live by it. Although there are parts of scripture that may be difficult to understand, its truths can be revealed by simpler verses. This understanding goes back to the centrality of God. Man is not permitted to interpret scripture however he wants. That would make him an authority over God’s Word. Instead, the appropriate understanding is that scripture must interpret itself.
The perspicuity of scripture has helped generations clearly understand God’s Word and draw from it doctrinal truths summarized in Scripture. Through the works of faithful men, Reformed Theology has been summed up in the Westminster Standards and the Three Forms of Unity. These are not inerrant or infallible documents; neither do they claim to be. Yet these confessions are beneficial in aiding believers to build a Biblical framework by which to read scripture, glorify God, and confess faith.
Along with the Reformed confessions, Reformed Theology holds to the Five Solas and the Five Points of Calvinism. The Five Solas were a response to the heresies of the Roman Catholic Church, whereas the Five Points of Calvinism were a response to the Remonstrants (Arminians). The Solas affirm that the rule for a believer is scripture alone, and that their salvation is by grace alone by faith alone in Christ alone, and all is for the Glory of God alone. Calvinism is articulated in the acronym T.U.L.I.P. In brief, it highlights God’s sovereignty to have mercy on whom He wills.