Ephesians 4, The Old vs. The New

Ephesians 4
Unity in the Body of Christ
1 As a prisoner for the Lord, then, I urge you to live a life worthy of the calling you have received. 2 Be completely humble and gentle; be patient, bearing with one another in love. 3 Make every effort to keep the unity of the Spirit through the bond of peace. 4 There is one body and one Spirit—just as you were called to one hope when you were called— 5 one Lord, one faith, one baptism; 6 one God and Father of all, who is over all and through all and in all.
7 But to each one of us grace has been given as Christ apportioned it. 8 This is why it says: "When he ascended on high, he led captives in his train and gave gifts to men." 9 (What does "he ascended" mean except that he also descended to the lower, earthly regions? 10 He who descended is the very one who ascended higher than all the heavens, in order to fill the whole universe.) 11 It was he who gave some to be apostles, some to be prophets, some to be evangelists, and some to be pastors and teachers, 12 to prepare God's people for works of service, so that the body of Christ may be built up 13 until we all reach unity in the faith and in the knowledge of the Son of God and become mature, attaining to the whole measure of the fullness of Christ.
14 Then we will no longer be infants, tossed back and forth by the waves, and blown here and there by every wind of teaching and by the cunning and craftiness of men in their deceitful scheming. 15 Instead, speaking the truth in love, we will in all things grow up into him who is the Head, that is, Christ. 16 From him the whole body, joined and held together by every supporting ligament, grows and builds itself up in love, as each part does its work.
Living as Children of Light
17 So I tell you this, and insist on it in the Lord, that you must no longer live as the Gentiles do, in the futility of their thinking. 18 They are darkened in their understanding and separated from the life of God because of the ignorance that is in them due to the hardening of their hearts. 19 Having lost all sensitivity, they have given themselves over to sensuality so as to indulge in every kind of impurity, with a continual lust for more.
20 You, however, did not come to know Christ that way. 21 Surely you heard of him and were taught in him in accordance with the truth that is in Jesus. 22 You were taught, with regard to your former way of life, to put off your old self, which is being corrupted by its deceitful desires; 23 to be made new in the attitude of your minds; 24 and to put on the new self, created to be like God in true righteousness and holiness.
25 Therefore each of you must put off falsehood and speak truthfully to his neighbor, for we are all members of one body. 26 "In your anger do not sin": Do not let the sun go down while you are still angry, 27 and do not give the devil a foothold. 28 He who has been stealing must steal no longer, but must work, doing something useful with his own hands, that he may have something to share with those in need.
29 Do not let any unwholesome talk come out of your mouths, but only what is helpful for building others up according to their needs, that it may benefit those who listen. 30 And do not grieve the Holy Spirit of God, with whom you were sealed for the day of redemption. 31 Get rid of all bitterness, rage and anger, brawling and slander, along with every form of malice. 32 Be kind and compassionate to one another, forgiving each other, just as in Christ God forgave you.

Early on in this chapter we are called to: be humble, be patient, gentle, bearing with each other, create unity through peace. The life of a Christian should reflect these character traits.

Building Up Christ
Verses 11 and 12 tell us that there are many different callings for Christians, but all positions should prepare God's people for works of service, so that the body of Christ may be built up. Not everyone should preach nor are there that many teachers, but we should all be doing something to build up Christ.

The NOW
The last half of the passage is full of clear expectations:
-no longer live as the Gentiles do
-put off your old self
-made new in the attitude of your minds
-speak truthfully to his neighbor
-Do not let any unwholesome talk come out of your mouths

I guess the best testimony for a Christian would be through one's lifestyle. Can your neighbors sense something different about you or do you live as the Gentiles do? When you accepted Christ did you put off your old self, or do you hold on to a lot of things that do not build up Christ? Is your speech ALWAYS building up Christ or are there times that your conversation leads others to believe you are no different than anyone else?

The best example of puting off the old self once again is Paul when he was blinded by God's light and called to serve God instead of persecute Christians. Not all of our experiences can be as dramatic as Paul's, but we are all called to do the same thing no matter what your position.