And ye shall know the truth (kai gnōsesthe tēn alētheian). Truth is one of the marks of Christ (Joh 1:14) and Jesus will claim to Thomas to be the personification of truth (Joh 14:6). But it will be for them knowledge to be learned by doing God’s will (Joh 7:17). The word is from alēthēs (a privative and lēthō, to conceal, unsealed, open). See also Joh 8:40, Joh 8:44, Joh 8:45.
And the truth shall make you free (kai hē alētheia eleutherōsei humas). Future active indicative of eleutheroō, old verb from eleutheros (from erchomai, to go where one wishes and so free). One of Paul’s great words for freedom from the bondage of the law (Rom 6:18; Gal 5:1). The freedom of which Jesus here speaks is freedom from the slavery of sin as Paul in Rom 8:2. See Joh 8:36. This freedom is won alone by Christ (Joh 8:36) and we are sanctified in truth (Joh 17:19). In Joh 1:17 truth is mentioned with grace as one of the marks of the gospel through Christ. Freedom (intellectual, moral, spiritual) is only attainable when we are set free from darkness, sin, ignorance, superstition and let the Light of the World shine on us and in us.