Here are some great (and lengthy) articles and resources to encourage our trust in the reliability of scripture from external sources.

First, 10 basic facts about the New Testament canon:

1. “The New Testament Books are the Earliest Christian Writings We Possess”
2. “Apocryphal Writings Are All Written in the Second Century or Later”
3. “The New Testament Books Are Unique Because They Are Apostolic Books”
4. “Some NT Writers Quote Other NT Writers as Scripture”
5. “The Four Gospels are Well Established by the End of the Second Century”
6. “At the End of the Second Century, the Muratorian Fragment lists 22 of Our 27 NT Books”
7. “Early Christians Often Used Non-Canonical Writings”
8. “The NT Canon Was Not Decided at Nicea—Nor Any Other Church Council”
9. “Christians Did Disagree about the Canonicity of Some NT Books”
10. “Early Christians Believed that Canonical Books Were Self-Authenticating”

Next, 10 misconceptions about the New Testament canon:

1. The term “canon” can only refer to a fixed, closed list of books
2. Nothing in early Christianity dictated that there would be a canon
3. The New Testament authors did not think they were writing Scripture
4. New Testament books were not regarded as scriptural until around 200 A.D.
5. Early Christians disagreed widely over the books which made it into the canon
6. In the early stages, apocryphal books were as popular as the canonical books
7. Christians had no basis to distinguish heresy from orthodoxy until the fourth century
8. Early Christianity was an oral religion and therefore would have resisted writing things down
9. The canonical gospels were certainly not written by the individuals named in their titles
10. Athanasius’ Festal Letter (367 A.D.) is the first complete list of New Testament books

If you can’t read through all that, or just want a quicker version, here is the author of those posts giving a short summary on the reliability of the New Testament canon:

Finally, here you can find a talk link to Southern Baptist Theological Seminary Old Testament lecturer Peter Gentry on the Reliability of the Old Testament. It runs for approximately 1 hour.