If the revelation of Jesus as the Son of God was yet another demonstration of the Creator God’s love for His world, and if the manifestation of His glory, in and through the Christ, was for the purpose of causing people to believe in Him (to acknowledge and worship Him as Creator) so that eternal life (an entrance into the purpose that the covenant God had always intended for those that He had created to bear His image) could be experienced (rather than the continual perishing under the reign of death that had been brought into the world and exacerbated by the other sons---Adam, Israel, Solomon), then the idea of being “in Christ” takes on an extreme importance.
Those that are in union with the Christ (in Christ) are said to be brought into that union, with such being demonstrated through the confession of Jesus as Lord of all (in both word and deed), by the power that is somehow inherent in the preached Gospel (Jesus is Lord). This power of the Gospel is understood to be somehow transmitted by the activity of the Spirit of the Creator God, as one of the manifestations of the very power that is said to have raised Jesus up from the dead, and which is still at work in this world according to the plan and purpose of the Creator God.
Additionally, those that are in union with the Christ are said to have been crucified and resurrected with Him, for the purpose of being kings and priests to the Most High God, along with the responsibilities implied by those titles. Indeed, to go beyond that, those that are in union with the Christ are identified as sons of God.
Those in union with the Christ are those that make up His church and are citizens of the kingdom of the Creator God (kingdom of heaven, rule of God)---a renewed people of the Creator (a new creation), charged with, among other things, reflecting the glory of their God into the world through kingdom-oriented and Spirit-inspired actions. Effectively, it could be said that those that are in union with the Christ are called to be Solomon’s, Israel’s, and Adam’s for the world, doing so with the mysterious power of the resurrection at their backs, as they speak and live the message of the Gospel, orienting their thoughts and their lives around the fact that Jesus is Lord.
This means that Christians are called to live a life that is set apart and demonstrably different in their engagement with the world. This does not mean that Christians hide away, buried underneath the weight of what could very well be a fruitless asceticism, withdrawn and distant from the world in a vain and conceited striving for a pseudo-holiness that is nothing more than a self-serving and selfish attempt to shrink back from the awesome responsibilities that attend this glorious union and its weighty demands.