When we understand covenant theology, our knowledge of God, our peace in our relationship with Him, and our grasp of what it means to live as His people grow deeper and richer.

Stephen G. Myers, GOD TO US – Covenant Theology in Scripture, 13.

So then this Scripture alone is the fundamental principle by which, and the material from which, every saving truth must be drawn. It is the rule and standard by which every true and also every false teaching about the things of God must be determined (Isa 8:20; Luke 16:29; Acts 17:10, 11). In sum, it is a self-convincing and irrefutable witness and Judge, namely by virtue of its own demonstrated proof by which every controversy which arises over divine matters must be judged (John 5:39, 45).

Synopsis of a Purer Theology, Vol. 1, 23.

God the Father, in the Son and through the Holy Spirit, is the first efficient cause of the writing of these individual books by his order and instigation (Exod 17:14; Jer 36:1[-4]; Rev 1:1, chapter 2, etc.). The ministers or instruments are holy servants of the Lord, ‘called by God and breathed upon by Him,’ and ‘driven’ by the Holy Spirit. Hence Scripture is called “God-breathed” (2 Tim 3:16; Rom 16:26; 2 Pet 1:20).

Synopsis of a Purer Theology, Vol. 1, 20.

. . . the divine law can depend on no-one except God himself, who is dependent on no creature. . . . so too Holy Scripture, the supernatural principle of all sacred teaching, and the unmoved rule of faith and moral conduct, can depend on nothing but God who has granted it, and on its own light, which He has put into it.

Synopsis of a Purer Theology, Vol. 1, 17.

For we admit freely that it is the Church’s duty to guard Holy Scripture, to preserve its integrity with all reverence and care, to vindicate it from people’s corrupting influence, to exhibit and prove its divine quality to others, whence it is called, “the pillar and bulwark of the truth,” by Paul in 1 Tim 3 [:15]. Be that as it may, from this no authority over Scripture should be drawn for the Church, but only service and proclamation, just as the edicts of leading civic officials do not get their authority from the heralds and servants, even though by these men they are made known and published.

Synopsis of a Purer Theology, Vol. 1, 16.

Even though the Old and New Testaments differ with respect to some of the tools whereby the teachings are administered (and also their circumstances), yet they agree as far as the substance is concerned. And the same Theology is advanced in both Testaments: God’s single will to redeem the human race and the one basic promise that salvation must be obtained through Christ (Gen 3:15 and 22:18; Acts 15:11, and 10:43, etc.).

Synopsis of a Purer Theology, Vol. 1, 7.

God is the chief efficient cause of Theology . . .

The instrumental cause of Theology is the Word of God, spoken through the mouth of men divinely inspired and called directly by God, and recorded in the holy books (1 Pet 1:12, 2 Pet 1:21, Acts 20:27, 1 Thess 2:13 and 4:8).

Synopsis of a Purer Theology, Vol. 1, 4-5.

The institution of the Supper later gave a visible clue that enables Christians to grasp the fuller meaning of Jesus’ “hard saying”(Jn. 6:60) about eating His flesh and drinking His blood.

“Lord’s Supper (Eucharist)” in ISBE, Vol. 3, 166.

In 1 Cor. 10 Paul refers to Israel’s being saved, revived, and nourished by miracles corresponding to the NT sacraments of baptism and the Lord’s Supper. Paul asserts that Christ’s presence in OT Israel was so real, and the spiritual blessing He bestowed to His people was so closely bound up with the miraculous physical help He gave them, that He could actually be identified with one of the objects He used in mediating His blessing to them — “that Rock was Christ”(v.4).

“Lord’s Supper (Eucharist)” by R. S. Wallace in ISBE, Vol. 3, 165.

That the apostolic preaching is nothing other than the various predictions made by the prophets, proclaimed as having been realized in Jesus Christ, means that, on the one hand, the apostolic preaching is both the key to understanding the Old Testament and the confirmation of its fulfillment, while, on the other hand, it is the Old Testament which shapes the whole of the Christian revelation itself.

ST IRENAEUS OF LYONS, ON THE APOSTOLIC PREACHING, TRANSLATED WITH AN INTRODUCTION BY JOHN BEHR, 13.