Being united means being joined together. Being united means that you share a common purpose. Again and again the Bible speaks of unity. We are to be united as brothers and sisters. We are to have unity in the church. We are to have unity in our families. We also are to be united with Christ. We cannot have any other true unity without having union with Christ.
The Bible says first we must receive Christ. Once we receive Jesus, then we are to walk with Him. The Apostle Paul writes often of walking with Christ. We are to continue the race. We are to press forward with Him. To the Colossians, he said they should regulate their lives so that they could live in this union with Jesus, even so much that we conform to Him.
Being united with Christ is not a difficult thing. Sadly people complicate this union. It is a simple union. A perfect union. A union like no other. It requires a heart for Jesus. It demands surrender. But it is simple and it is satisfying.
As you have therefore received Christ, [even] Jesus the Lord, [so] walk (regulate your lives and conduct yourselves) in union with and conformity to Him. – Colossians 2:6 [AMP]