"For as many as are led by the Spirit of God, they are the sons of God." Romans 8:14
Throughout the scripture there are many references to the same subjects. Sometimes God builds a case for us to consider and sometimes God does more than make it plain. This is one of those verses that makes it plain. Inside your Spirit resides the Spirit of God if you have been born again. That Spirit of God, God within, makes a path and leads you on that path. Every decision you make could be made with the mind of Christ by the Spirit of God if you were to invite the Spirit of God within to participate in your decision making.
Just as you invite the Holy Spirit of God to participate in your decision/s, the Spirit of God is inviting you to participate in God's decisions/direction/events. Over time what the Christian should be looking for in their walk/lifestyle is for what they are inviting God into, God is inviting them into. These are the Sons of God.
Too much emphasis has been put on the peripherals of Christianity and not enough on the spiritual connection. Even if you have devised some other formula to qualify your position in the kingdom of God, or if you do not believe that personal relationship is of any real importance in the overall salvation program, the Bible says that those who are led by the Spirit are the sons of God.
Why not hear what God says and learn to trust in His words? It has been my experience that many people who claim to be a Christian cannot claim to have any connection to the Spirit of God as in being led by the Spirit. I believe it is safer to read what God says and do it than to rely on unsubstantiated systems, devices, theologies, sciences or man made formulas when it comes to our relationship with God and our eternal destiny.