And he gave the apostles, the prophets, the evangelists, the shepherds and teachers,  to equip the saints for the work of ministry, for building up the body of Christ,  until we all attain to the unity of the faith and of the knowledge of the Son of God, to mature manhood, to the measure of the stature of the fullness of Christ,  so that we may no longer be children, tossed to and fro by the waves and carried about by every wind of doctrine, by human cunning, by craftiness in deceitful schemes.
The couple verses here boil down to what is expected of us when it comes to building up the body of Christ, and why.
The Lord cave us church leaders in order to equip the saints for the work of ministry. Believers are not meant to rely only on the leaders for ministry, but to get fed and go out themselves and minister in building up the body of Christ.
We are the saints. In Christ, our purpose is to build up the body of Christ into mature followers of Jesus. We should be building the body to be closer and closer to the fullness of Christ.
The individuals in the body, and therefore the body of Christ, needs to be mature enough not to get fooled by false doctrine or worldly deceit. There are plenty of both nowadays so we all need good discernment and maturity. For instance, we need to teach one another about the tricks of charismatic speakers, wily politicians, and false doctrinal teachers. We need to sharpen one another to make our body mature.
We are called to share the gospel. Share with others what Jesus has done in our lives. Share the love and joy we get for free as Christ followers. Share the grace we don’t deserve. All of this will build up the unity of the body of Christ.
Lord thank You for equipping me to build a body focused on You and the fullness only You can provide. Help me to share the gospel with unbelievers or those who are undecided, and help me to sharpen my fellow believes so that we will be in unity on the big issues and not be fooled by Satan’s mouthpieces. In Jesus’ Holy and Mighty name I pray. Amen.