But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:
1 Corinthians 1:30 (KJV)
Being in Christ Jesus is referring to our union with Christ. The moment we surrender our lives to the Lord, we are joined unto Him through the Holy Spirit who lives in us. Jesus now has become our wisdom, our righteousness, our sanctification, and our redemption. And so let us remember to not look to ourselves, but to Jesus. Being in Christ means that He has become our sufficiency unto whatever need may arise; and as we meditate daily on this truth, accepting it in our hearts by faith, we will see the fruits of it showing up in our lives.