From Christian Forum's Doctrinal Statement of Faith: "We believe that the Bible is inspired by God in its entirety, and is without error in the original autographs, a complete and final written revelation from God."
Question: Where does the Bible say it is the soul source of revelation from God?
It doesn't, but it does imply that it is sufficient for all of Christian life, faith, and godliness, and that it is the only inspired and infallible authority on such things, making it the final authority. Of course, it also depends somewhat on what you mean by "revelation."
Joh 16:13 When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come. (ESV)
The results of this are the inspired writings of the NT.
Joh 20:30 Now Jesus did many other signs in the presence of the disciples, which are not written in this book;
Joh 20:31 but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name. (ESV)
John certainly believed his gospel was sufficient for knowing and believing that Jesus is who he said he is, and so one could be saved.
Act 17:11 Now these Jews were more noble than those in Thessalonica; they received the word with all eagerness, examining the Scriptures daily to see if these things were so. (ESV)
They searched the Scriptures for the truth and didn’t seek additional divine revelation.
Gal 1:8 But even if we or an angel from heaven should preach to you a gospel contrary to the one we preached to you, let him be accursed.
Gal 1:9 As we have said before, so now I say again: If anyone is preaching to you a gospel contrary to the one you received, let him be accursed. (ESV)
Not even an apostle could change what had already been taught.
2Th 2:1 Now concerning the coming of our Lord Jesus Christ and our being gathered together to him, we ask you, brothers,
2Th 2:2 not to be quickly shaken in mind or alarmed, either by a spirit or a spoken word, or a letter seeming to be from us, to the effect that the day of the Lord has come. (ESV)
A warning against additional, non-apostolic revelation.
1Ti 5:18 For
the Scripture says, “You shall not muzzle an ox when it treads out the grain,”
and, “
The laborer deserves his wages.” (ESV)
In the first quote, Paul is quoting Deut 25:4. In the second, he is quoting Luke 10:7 (cf. Matt 10:10), saying that it is Scripture. Paul is explicitly saying that Luke's gospel is Scripture, on par with the OT Scriptures.
2Ti 3:14 But as for you, continue in what you have learned and have firmly believed, knowing from whom you learned it
2Ti 3:15 and how from childhood you have been acquainted with the sacred writings, which are able to make you wise for salvation through faith in Christ Jesus.
2Ti 3:16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,
2Ti 3:17 that the man of God may be complete, equipped for every good work. (ESV)
All of Scripture is inspired and is all that is necessary for “the man of God [to] be complete, equipped for every good work.”
2Pe 3:15 And count the patience of our Lord as salvation, just as our beloved brother Paul also wrote to you according to
the wisdom given him,
2Pe 3:16 as he does in
all his letters when he speaks in them of these matters. There are some things in them that are hard to understand, which the ignorant and unstable twist to their own destruction, as they do
the other Scriptures. (ESV)
First Peter says that Paul wrote "according to the wisdom given him," which means what he wrote was based on wisdom from God (inspired). Then Peter equates Paul's letters with "the other Scriptures," being the OT. Peter is very strongly implying that he thinks Paul's writings are Scripture in the same way the OT books are Scripture.
Jud 1:3 Beloved, although I was very eager to write to you about our common salvation, I found it necessary to write appealing to you to contend for the faith that was once for all delivered to the saints. (ESV)
If “the faith . . . was once for all delivered to the saints,” that means it is complete and there is nothing that can or should be added to what we have.
Putting that all together then, Paul's writings were seen as Scripture, so it stands to reason that all the Apostle's writings are Scripture. It also stands to reason that since Luke's gospel was seen as Scripture, that all the writings of close associates of the Apostles were seen as Scripture. That is the entire NT.
There is nothing to suggest that there would be additional revelation or that additional revelation was or should be needed. It is implied that what we have in the Bible is Scripture and it is sufficient. Indeed, there are two warnings to not add to what God has already stated:
Pro 30:5 Every word of God proves true; he is a shield to those who take refuge in him.
Pro 30:6 Do not add to his words, lest he rebuke you and you be found a liar. (ESV)
Rev 22:18 I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book,
Rev 22:19 and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book. (ESV)
There is also an implied warning about the same, as it could be just adding worldly philosophy:
Col 2:8 See to it that no one takes you captive by philosophy and empty deceit, according to human tradition, according to the elemental spirits of the world, and not according to Christ. (ESV)
