“You, however, continue in the things you have learned and become convinced of, knowing from whom you have learned them, and that from childhood you have known the sacred writings which are able to give you the wisdom that leads to salvation through faith which is in Christ Jesus.”

2 Timothy 3:14-15

R. C. Sproul:

“In the sixteenth century, the Reformers declared their total confidence in what they called the perspicuity of Scripture. What they meant by that technical term is the clarity of Scripture. They maintained that the Bible is basically clear and lucid. It is simple enough for any literate person to understand its basic message.”

John Owen:

“…The Holy Spirit hath so disposed of the Scripture that the mind of God in all things concerning our faith and obedience…is clearly revealed therein.

“…In those very fords and appearing shallows of this river of God where the
lamb may wade, the elephant may swim. Every thing in the Scripture is so plain that the meanest believer may understand all that belongs unto his duty or is necessary unto his happiness; yet is nothing so plain but that the wisest of them all have reason to adore the depths and stores of divine wisdom in it….

“It is supposed, when we assert the clearness and perspicuity of the Scripture, that there is unto the understanding of it use made of that aid and assistance of the Spirit of God concerning which we do discourse. Without this the clearest revelations of divine supernatural things will appear as wrapped up in darkness and obscurity: not for want of light in them, but for want of light in us. Wherefore, by asserting the necessity of supernatural illumination for the right understanding of divine revelation, we no way impeach the perspicuity of the Scripture. All things wherein our faith and obedience are concerned are clearly declared there…”

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Lamb: FreeFoto.com
Ichetucknee Springs, Florida: Site of my mother’s family reunion since 1933.
R. C. Sproul, Knowing Scripture, 1977, p. 15.
I’d add that you don’t even have to be literate to understand the Bible’s basic message about
what it means to believe in Jesus.  Neither of my children could read when they became
Christians.
John Owen, The Works of John Owen, edited by Rev. William H. Goold, Vol. IV, pp. 193-194.