Heinrich Heppe, Reformed Dogmatics:
The attributes of “sufficiency” and “perpetuity” belong to H. Scripture, because the whole doctrine of it rests upon a foundation, from which all revealed truths are derived and in which all doctrines of salvation are already contained in essence. This basic truth of Scripture is the comfortable doctrine, that Christ is the way, the truth and the life and the believer’s inalienable possession. In the Son become man not only does the truth of the law appear afresh: in Him it is also the eternal, forgiving grace of the Father; that is, law and gospel offered to the world, and not just offered but given to believers, so that they can never lose it again. This then is the sum of all doctrines of Scripture, that Christ is not just the salvation of the world in general but is also “my” salvation, and that because “I” have become “the Lord’s property”, I shall likewise remain so for ever. The basic foundation of all revealed truths in Scripture is thus the covenant of God with believers in Christ.