Revelation is a supernatural communication of divine truth presented to men (Deut 29:29), of that which they otherwise would not know, the Scriptures (Old and New Testament) the chief locus (Ps 138:2) of the Revelation.
Deuteronomy 29:29 The secret things belong unto the LORD our God: but those things which are revealed belong unto us and to our children for ever, that we may do all the words of this law.
Psalm 138:2 I will worship toward thy holy temple, and praise thy name for thy lovingkindness and for thy truth: for thou hast magnified thy word above all thy name.
Inspiration is the term used to describe how the Scriptures were given by God, men supernaturally guided to express exactly what God intended (verbal-plenary), therefore that word spoken in old time by holy men of God is infallible, and preserved for us today (2 Pet 1:19-21; 2 Tim 3:16; Jer 1:9; Ps 100:5; Ps 12:7).
2 Peter 1:19 We have also a more sure word of prophecy; whereunto ye do well that ye take heed, as unto a light that shineth in a dark place, until the day dawn, and the day star arise in your hearts: 20 Knowing this first, that no prophecy of the scripture is of any private interpretation. 21 For the prophecy came not in old time by the will of man: but holy men of God spake as they were moved by the Holy Ghost.
2 Timothy 3:16 All scripture is given by inspiration of God, and is profitable for doctrine, for reproof, for correction, for instruction in righteousness:
Jeremiah 1:9 Then the LORD put forth his hand, and touched my mouth. And the LORD said unto me, Behold, I have put my words in thy mouth.
Psalm 100:5 For the LORD is good; his mercy is everlasting; and his truth endureth to all generations.
Psalm 12:7 Thou shalt keep them, O LORD, thou shalt preserve them from this generation for ever.
Illumination refers to the Spirit enlightening the understanding of man whereby the meaning of Scripture is understood by the believer (1 Cor 2:10-14; 2 Cor 4:6; Eph 1:18; 2:1; John 16:13; Isa 29:18). The Spirit of God acts immediately upon the soul (John 3:7).
1 Corinthians 2:10 But God hath revealed them unto us by his Spirit: for the Spirit searcheth all things, yea, the deep things of God. 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. 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. 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. 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.
2 Corinthians 4:6 For God, who commanded the light to shine out of darkness, hath shined in our hearts, to give the light of the knowledge of the glory of God in the face of Jesus Christ.
Ephesians 1:18 The eyes of your understanding being enlightened; that ye may know what is the hope of his calling, and what the riches of the glory of his inheritance in the saints,
Ephesians 2:1 And you hath he quickened, who were dead in trespasses and sins;
John 16:13 Howbeit when he, the Spirit of truth, is come, he will guide you into all truth: for he shall not speak of himself; but whatsoever he shall hear, that shall he speak: and he will shew you things to come.
Isaiah 29:18 And in that day shall the deaf hear the words of the book, and the eyes of the blind shall see out of obscurity, and out of darkness.
John 3:7 Marvel not that I said unto thee, Ye must be born again.