The Solid Foundation is the Verbally inspired Word of God. Without this Foundation we could know literally nothing about God. All Christian teaching and doctrine is based on the Verbal, Plenary, Inspired Word of God.
This is the reason that theological liberals so rabidly attack the Holy Scriptures. Since the beginning of time, Satan has attempted to pervert the Word of God. In his temptation of Eve in the Garden of Eden he pervert what God had said to Eve.
If you are going to be a sound and strong Biblical Christian you must know the Word of God. The Devil does everything he can to get you to doubt the full authority of the Word of God.
Jesus had memorized the Word of God and used it in his quotations of it to the Devil as his defense. I believe that every Christian should memorize key passages and verses of Scripture to fortify themselves for the battle with the World, the Flesh, and the Devil. 1 John 2:15-17
1 John 2:15-17 (KJV)
15 Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him.
16 For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.
17 And the world passeth away, and the lust thereof: but he that doeth the will of God abideth for ever.
Scripture Memory Fellowship is a good organization to help you memorize the Scriptures. http://scripturememoryfellowship.org/
Numbers 6:24-26 (KJV)
24 The LORD bless thee, and keep thee:
25 The LORD make his face shine upon thee, and be gracious unto thee:
26 The LORD lift up his countenance upon thee, and give thee peace.
Rev. Thomas L. Clark – Phil, 3:14