Then there is another very striking passage. In Romans 8:9, Paul says: “Now, if any man have not the Spirit of Christ, he is none of His.” That ought to settle the question, even though one may have gone through all the external forms that are considered necessary by some to constitute a member of a Church. Read Paul’s life, and put yours alongside of it. If your life resembles his, it is a proof that you are born again—that you are a new creature in Christ Jesus.
But although you may be born again, it will require time to become a full-grown Christian. Justification is instantaneous; but sanctification is a lifework.
We are to grow in wisdom. Peter says “Grow in grace, and in the knowledge of our Lord and Saviour Jesus Christ” (2 Peter 3:18); and in the first chapter of his Second Epistle, “Add to your faith virtue; and to virtue knowledge; and to knowledge temperance; and to temperance patience; and to patience godliness; and to godliness brotherly kindness; and to brotherly kindness charity. For if these things be in you and abound they make you that ye shall neither be barren nor unfruitful in the knowledge of our Lord Jesus Christ.”
So that we are to add grace to grace.
A tree may be perfect in its first year of growth; but it does not attain its maturity. So with the Christian: he may be a true child of God, but not a matured Christian.
The eighth of Romans is very important, and we should be very familiar with it. In the fourteenth verse the apostle says: “For as many as are led by the Spirit of God they are the sons of God.”
Just as the soldier is led by his captain, the pupil by his teacher, or the traveller by his guide; so the Holy Spirit will be the guide of every true child of God.