Years ago, when I was first called to preach, some preacher friends let me read what I will call “outlaw books”. These were books that would not be accepted by most Independent Fundamental Baptist. The books basically exposed our shallow evangelism and phony conversions. The preachers who gave them to me in all likelihood never dreamed that I would take their “outlaw books” seriously. {Looking back it doesn’t seem that they took them too seriously} Some of the authors leaned toward Arminian-ism and others were Calvinistic. But I believe their message is still much needed. I recommend them to you with the prayer that they will set your soul on fire as they have mine.
Bro. Shawn
Walter Chantry, The Banner of Truth Trust P.O. Box 621, Carlisle, Pennsylvania1701
Why Revival Tarries and Sodom had no Bible
Leonard Ravenhill, These two books are available at just about any good Christian book store.
Evangelism {If I’m not mistaken this is a compilation of lectures given at BJU in the 1950’s}
Biblical Salvation {Formerly Full Salvation}
James A. Stewart,
Available from, REVIVAL LITERATURE P. O. Box 6068 Asheville, NC28816
1-800-252-8896
{Disclaimer-we may not agree with every author or source on every subject}
The Christian Excavator 
Actually there are many more of which AW Tozer’s books are the milder. Then there is Paul Washer and John Piper and Bible commentary by John MacArthur and of course AW Pink, Charles Spurgeon and so on.
But actually the most difficult book for hunanistically inclined minds with the most hard sayings is the Bible. Everyone needs to just read the Bible and quit reading other books which try to tell you what the Bible says. If everyone would just lay aside their prejudices and try to read the Bible afresh accepting it for what it says one will find out fairly quickly that what it says doesn’t line up with what is preached in 90% plus of today’s modern churches.
Of course one must be born again for without the assistance of the Holy Spirit it is not possible to understand scripture. Also one needs to spend much time seeking God in prayer for this is where much of the illumination comes. Just remember as in Heb. 11:6 God is a rewarder of those who diligently seek him. If you make little effort in your Bible study but depend on others for your theology and doctrine then God help you!
Also Bible versions do make a difference. God has shown me which version to read. Rather than get into an argument of Bible versions I suggest you ask the Spirit in you what version you should read.
As regarding the necessity of being born again and the indwelling of the Spirit to understand scripture I submit:
1Co 2:11 For what man knoweth the things of a man, save the spirit of man which is in him? even so the things of God knoweth no man, but the Spirit of God.
1Co 2:12 Now we have received, not the spirit of the world, but the spirit which is of God; that we might know the things that are freely given to us of God.
1Co 2:13 Which things also we speak, not in the words which man’s wisdom teacheth, but which the Holy Ghost teacheth; comparing spiritual things with spiritual.
1Co 2:14 But the natural man receiveth not the things of the Spirit of God: for they are foolishness unto him: neither can he know them, because they are spiritually discerned.