In his book, Introduction in Research in English Literary History, C. Sanders sets forth three tests of reliability employed in general historiography and literary criticism.{10} These tests are:

1. Internal evidence (what the document claims for itself).

2. Bibliographical (i.e., the textual tradition -- from the original document to the copies and manuscripts of that document we possess today).

3. External evidence (how the document squares or aligns itself with facts, dates, persons from its own contemporary world).

   We'll look now at the internal evidence for the Bible's reliability. It's fair to ask the "defendant' what it says about itself.

1. Self-witness
   1. Old Testament

      The Old Testament is full of instances of God speaking (over 3800 occasions). God has spoken to his people since they were created (Gen. 1:28-30; 2:9ff. The nation of Israel was established by the spoken and written word of God (Ex. 24:4,12; 32:15,16). Prophets were told to write down what God said (Is. 8:1; 30:8; Jer. 25:13).

      Jesus and the apostles testified to the authority of the Old Testament writings. Jesus said that Scripture wasn't to be broken (Mt. 5:17-19). In other places He quoted from Scripture; never did he hint that Scripture was flawed or lacked authority (Mt. 19:4,5; Mk. 7:8-13; 12:36; Lk. 11:51; Jn. 10:35). The apostles likewise noted the divine source of the O.T. Scriptures (11 Tim. 3:16-17; 1 Pe. 1:10,11; 11 Pe. 3:15-16).

      The Old Testament is so tied to God's word that there are times when the Bible is given credit for saying something God said, and vice versa (Gen. 12:1-3/Gal. 3:8; Ex. 20:12; 21:17/ Mt. 15:4-6; Gen. 2:24/ Mt. 19:4,5; Ps. 95:7f / Heb.3:7f).

   2. New Testament

      
      The writer of Hebrews makes clear that the message of Jesus was on par with the Old Testament. God had spoken earlier through the prophets (OT); now He was speaking through Jesus. Thus, Jesus' words recorded in the New Testament are God's words (see Jn.14:10; 17:8). 

      The apostles in turn were taught by Jesus. They didn't only have direct teaching from Jesus, however. They also were promised that the Spirit would remind them of what Jesus had said Jn.14:26; 16:12,13; see also Mt.10:19ff; Eph.3:4,5). The apostles were to be Christ's spokesmen; their words carried his authority. Paul explicitly declared that the message he delivered was from God (II Thess.2;15; I Cor.4:37; Gal-1:11,12)
      .
      Thus, the testimony of the New Testament, like the Old, is that it is God's message or word.

2. Consistency of the message

   The consistency of the biblical message is remarkable considering that it was written over a span of approximately 1500 years by around 40 authors of  different backgrounds writing in different places
   and covering controversial subjects, but all being unified in the message they delivered. By itself this doesn't prove divine origin, but it at least indicates that there is something special about the Bible and that it's message should be heard.