Here are some suggestions to answer the question. The very fact that a person asks such a question seriously, is itself an indication that one is growing. If we never ask ourselves such questions, then we have reason to question if we have spiritual life.

One question to put to ourselves would be: "Do we thirst more for God than we used to?" It is none less than Jesus Christ Himself who assures us that "hungering and thirsting after righteousness" is the indisputable mark of belonging to the Kingdom of God in the Beatitudes. Ultimately, righteousness can only be found in Christ.

A second clue to growing as a Christian is if we grieve over sins which we did not grieve over previously, even although we were converted for many years. Surely if we are growing in Christ's image we will become more sensitive to sin and therefore we should be more heavily burdened when we do wrong.

A very real mark of growth in the Christian life is if we can forgive easier and quicker than we used to.

Many fail to realize the importance of being able to forgive. Jesus Christ effectively made this a condition of salvation in His teaching on prayer (Matt 6:15 and Mark 11:26). Being "born again" means having the same spirit as God has. God is ready to forgive. If we have hesitations about forgiving or require a long period of time before we will forgive, it demonstrates that we are different from God.

A final mark of Christian growth that we would mention is the spirit of "discernment". The Holy Spirit, which indwells every believer, is called in the Bible the spirit of "understanding". A young child may be a real human being yet have little understanding or discernment until it grows up. Similarly, a true Christian ought to become more discerning as he grows up. They should learn from experiences, disappointments and strange providences.

A spirit of discernment is a great blessing but can only be cultivated through time.