Some things in life, like the grace of God, are free! Here are some great FREE Christian resources for your edification:

Bible/Bible Software/Bible Commentaries

• Bible Commentaries Online-a website that links to all the free commentaries scattered online, many of which you can download onto your hard drive. You can download complete sets of the International Critical Commentary, Keil & Delitzsch, Matthew Henry’s, and Calvin’s commentaries from here as well.
• Olive Tree (Mac/Windows)-the best Bible Reader/Study App imo. Many of its resources are free. Its paid modules are 10-50% cheaper than those of expensive Bible Softwares like Accordance, Bible Works, and Logos, but nearly as comprehensive and powerful. Bible Explorer (Mac/Windows), E-Sword (Windows), Eloquent (Mac; formerly known as MacSword), the Sword (Windows) are also free Bible softwares that do similar things with a lot of free modules and books.
• Blue Letter Bible-the most extensive online Bible resource, complete with commentaries, concordances, articles, maps, outlines, encyclopedias, devotionals, audio, video, and numerous translations including even the Septuagint and the Latin Vulgate. For a similar website that is more streamlined see Bible Gateway.
• Greek Bible-the Greek New Testament based on the Nestle-Aland 26th Edition (NA26). Equipped with definition and parsing for every word. SBL’s (Society of Biblical Literature) Greek New Testament in eBook format is available for download through OSNOVA.

Christian Classics

• Christian Classics Ethereal Library-a gargantuan resource for all Christian classics, including Calvin’s Commentaries on the Bible and St. Augustine’s City of God. You can read online or download the pdf files.
• Early Christian Writings-a great website featuring early Christian writings such as the Didache and Irenaeus’s Against Heresies.
• New Advent-a Catholic website that makes the Catholic Encyclopedia, the entire Summa Theologica of Thomas Aquinas, writings of the Church Fathers, the Bible (w/ three-column view of Septuagint, Douay-Rheims, and Vulgate, with terms linked to the Catholic Encyclopedia and commentary from various sources peppered throughout), and a Library of official Catholic documents.
• The NTS Library-a collection of free pdf Christian books ranging from devotional classics to theological treatises. Includes popular titles such as A.W. Tozer’s Pursuit of God, Brother Lawrence’s Practice of the Presence of God, Thomas à Kempis’s Imitation of Christ, John Bunyan’s Pilgrim’s Progress, and Charles Hodge’s Systematic Theology.
• Monergism & Bring the Books-an index of classic works by Puritans.

Missions

• Operation World-information intended to assist you in praying for every country in the world (e.g. % Christian, unreached people groups, prayer needs, etc.). For more detailed, though a little outdated, information on people groups see the Joshua Project. The CIA World Fact Book is also a useful database.

Music

• Cyber Hymnal-the definitive place for all things related to Christian hymns: hymn background, lyrics, composer info, even an audio playback feature.
• Higher Praise-the overwhelmingly comprehensive collection of chord/lyric sheets for Christian praise & worship music.

Theological Education

• Bible Training-audio lectures from renowned theological educators such as Douglas Stuart, Craig Blomberg, Bryan Chapell, Timothy Tennent, John Piper, and Ben Witherington. Registration is free.
• God-Centered-a compilation of resources for exegesis and theology. Includes links to useful websites and free online journals (Trinity, Denver, Princeton, etc.).
• Hebrew Syntax-tools and resources for those studying Biblical Hebrew, as well as limited resources for Biblical Greek, Aramaic, Syriac, and Ugaritic.
• Visual Greek-a visual tool for learning Greek vocabulary.

Miscellaneous

• Free Christian Resources-self-explanatory, a website “dedicated to finding the best high quality and edifying free Christian resources for you.” Features free Christian songs, books, Bible studies, sermons, and even clip art.