"He shall abide before God for ever: O prepare mercy and truth, which may preserve him." - Psalm 61:7
"Withhold not thou thy tender mercies from me, O LORD: let thy lovingkindness and thy truth continually preserve me." - Psalm 40:11
"O send out thy light and thy truth: let them lead me; let them bring me unto thy holy hill, and to thy tabernacles." - Psalm 43:3
It is quite clear from these quotations from the Psalms that truth, that is God's Truth as expressed in the Scriptures, is one of the requirements for eternal life and that without a belief in the Truth there is no hope. Belief in God's Truth, which includes obedience to His commandments, gives light to guide as evidenced from the following quotation when speaking of the Word (Greek logos) "In him [or it] was life; and the life was the light of men" (John 1:4).