Paul tells us that our lives will be revealing Christ if we belong to Him. "And they that are of Christ Jesus have crucified the flesh with the passions and lusts thereof" (Galatians 5:24). He then goes on to make it even plainer in 6:7-8, "Be not deceived; God is not mocked; for whatsoever a man soweth, that shall he also reap. For he that soweth unto the Spirit shall of the Spirit reap eternal life."
Our glorying should always be in what God has done. If there is going to be glorying, let it be in the cross of our Lord. The cross is what was provided to bring those who believe from the old creation into the new creation, from a place of complete rebellion to a place of faith, from a place of death to a place of life. Regeneration means the indwelling of the Spirit in the lives of those who believe. Justification is what God has done for us; regeneration is what God does in us. The cross shows each one of us what God thinks of the old creation and also reveals His love, in that we now may be partakers of His new creation.
This new creation is the answer to every question that may come into our minds, because the new creation is Christ. Not a historical Christ, but the living Christ who has come to indwell every believer by the Spirit-not automatically but by faith. We do not receive anything automatically from God; everything comes by faith, and faith always has Christ as its goal.
How can anyone live a Christian life without the indwelling of the Spirit? Any life lived in any way other than in and by the Spirit is only self bringing the works of its own hands and wanting acceptance from God. This is completely contrary to God's plan of salvation and what God has done by sending Christ to die for mankind on the Cross. Why does man want to make it so hard? Why does man want to come to God in his own way rather than God's way? These questions are answered by revealing sin in the heart of man. Sin has blinded man; he cannot know the ways of God. Only as man is willing to repent, to turn from the way he is going and turn to God, can he know the way of faith. It is the Spirit that has drawn each one who comes to repentance, but it is only faith that can bring each one to a place of knowing God by His indwelling.
Peter told the crowds on the day of Pentecost what they must do: "Repent and be baptized, and you shall receive the Holy Spirit." Baptism is a testimony that we believe what God has done at the cross, and that we accept God's judgment of the old and see that we have been brought into the new by His resurrection. Baptism identifies us with Christ, with who He is and what He has done for us. Then it is the Holy Spirit who comes and makes the life of God a reality within us. Why do we ever think doctrine and human knowledge can give us eternal life?