@Mkchissus While that is a question I think we are all continually growing in our understanding of, here are a few of my own thoughts. I believe the key passage is Colossians 3 because it offers a very easy to understand picture - to be in Christ is to be clothed in Christ - to put off the old self and put on the new self. Generally this image is easy for people to grasp. You could have a student wear a muddy, filthy jacket or robe, take it off and replace it with a clean, white robe. We are clothed in the righteousness of Christ and have been given eternal life. Nothing, not even death, can now separate us from the love of God.
But the great thing about Colossians 3 is that it emphasizes our need to continually, daily walk in the Spirit by crucifying the old man and putting on the new man. We are new creatures in Christ - so every day let’s wake up and clothe ourselves with the love and grace of Christ as we praise Him and love others.
So being ‘in Christ’ is two things:
- A position - when we are saved we are ‘in Christ’ and nothing can separate us from His love
- An action / choice - each day we choose to walk in the Spirit - to put on the new man and daily die to the old man of sin
Colossians 3:2-4,15-17 - Set your minds on things above, not on earthly things. 3 For you died, and your life is now hidden with Christ in God. 4 When Christ, who is your life, appears, then you also will appear with him in glory…Let the peace of Christ rule in your hearts, since as members of one body you were called to peace. And be thankful. 16 Let the message of Christ dwell among you richly as you teach and admonish one another with all wisdom through psalms, hymns, and songs from the Spirit, singing to God with gratitude in your hearts. 17 And whatever you do, whether in word or deed, do it all in the name of the Lord Jesus, giving thanks to God the Father through him.
Romans 8:38-39 - For I am convinced that neither death nor life, neither angels nor demons, neither the present nor the future, nor any powers, 39 neither height nor depth, nor anything else in all creation, will be able to separate us from the love of God that is in Christ Jesus our Lord.
Resisting Spiritual Forces of Evil
When it comes to evil spirits, I think the easiest explanation is that Jesus has authority over them because He is God. So saying ‘in Jesus’ name is not a magic spell. Consider the sons of Sceva - they did not know Jesus, so they could not call on His name. Saying ‘in Jesus’ name’ is tantamount to a prayer - ‘Dear God, please drive out these evil spirits by the authority of Jesus, who reigns over all things and whom I have come to know because of His matchless grace through the cross and the power of His resurrection’.
Acts 19:13-16 - Some Jews who went around driving out evil spirits tried to invoke the name of the Lord Jesus over those who were demon-possessed. They would say, “In the name of the Jesus whom Paul preaches, I command you to come out.” 14 Seven sons of Sceva, a Jewish chief priest, were doing this. 15 One day the evil spirit answered them, “Jesus I know, and Paul I know about, but who are you?” 16 Then the man who had the evil spirit jumped on them and overpowered them all. He gave them such a beating that they ran out of the house naked and bleeding.
However, I think the best advice when it comes to evil spirits is given in the article below - just focus on Jesus. The Gospel is the power of God to salvation and if we humble ourselves before God and resist the devil, he will flee (James 4:7).
I often hear Christians say they are fighting for victory. But the reality is that Christians fight from victory, not for victory. Jesus has already won the victory on our behalf, disarming and defeating every power of darkness that threatens us. So when “this world with devils filled should threaten to undo us, we will not fear, for God has willed his truth to triumph through us.”