Show me Your ways, O LORD; teach me Your paths. Lead me in Your truth and teach me, for You are the God of my salvation; on You I wait all the day. (Psalm 25:4-5, NKJV, emphasis added)
Sincerity and truth is experienced while waiting on God with great hope.
Therefore purge out the old leaven, that you may be a new lump, since you truly are unleavened. For indeed Christ, our Passover, was sacrificed for us. Therefore let us keep the feast (celebrate Christ as our Passover Lamb in communion), not the old leaven, nor with the leaven of malice and wickedness, but with the unleavened bread of sincerity and truth. (1 Corinthians 5:7-8, NKJV)
This text comes from a passage dealing with immorality in the Church. To be lead in the truth is to be lead away from the sin that once enslaved us and towards the new life surrendered to the will of our Redeemer and Lover of our souls.
Two choices are presented the people in Corinth (and to all people): (1) keep the old leaven (the old life of sin); or (2) keep the feast as being unleavened (no longer bound to sin). Leaven is yeast that causes bread to rise when you bake it. It only takes a little leaven to raise the bread. In the same way it only takes a little sin to make one corrupted, ruined, and out of the will of God. The disciple truly has one course to follow: to get rid of the old leaven and become new unleavened believers.
The old leaven is the life you had before Christ. Why would we want to return to that? The old leaven is described as malice and wickedness. The word for malice in the Greek is bad, as in wickedness being an evil habit of the mind. Wickedness in the Greek is the active outcome of the same. Thus wickedness is malevolence, not only doing evil, but being evil. So the effect of the old leaven is to create character that is evil, malevolent, and full of malice towards God first and other men second.
With the old leaven gone you may be a new lump. In Christ we are new creations (2 Corinthians 5:17 and Galatians 6:14-15). The New Testament teaches us that the old man is gone and the new man has arrived (Romans 6:1-14; Ephesians 4:17-24; and Colossians 3:1-11). Prayerfully meditate upon these passages of Scripture as you wait on the Lord to fully experience the transforming power of the Spirit of truth in your life.
The new lump is truly unleavened, or without sin. Because we are redeemed by Christ we no longer are enslaved to sin, a harsh taskmaster. Instead we are slaves to the Good Master, slaves of righteousness for holiness (Romans 6:15-23). Prayerfully meditate upon this passage and allow the Holy Spirit to minister to you and recognize the gift given to you.
We can then keep the feast. Now we can keep the Passover feast in celebrating Christ, our Passover Lamb slain for us so the wrath of God passes over us because Christ paid the penalty for our sin. Celebrate the achievement of our Lord as you wait upon Him with hope.
We can keep the feast with the unleavened bread of sincerity and truth. Now we see the end result of our being lead to all truth. The Greek word for sincerity includes the thought of being sincere in all purity. With the leaven gone we stand pure before our Creator King. We brought Him stained garments and He clothed us with all purity. Thank Jesus for His transforming work on the Cross for you as you continue wait upon Him, being lead in truth.