"But the fruit of the Spirit is love, joy, peace, longsuffering, gentleness, goodness, faith,
Meekness, temperance: against such there is no law."

                            -Galatians 5:22, 23

Would you say that things such as goodness, temperance, and longsuffering are virtues that a Christian should exercise just part of the time? Should we only be loving every once in a while? Of course not. These things are to flood our entire being, characterizing our new identity in Christ Jesus.

There is a reason why Paul calls these attributes "the fruit of the Spirit." If I was told by somebody to distinguish between two trees which one was the apple tree and which one was the pear tree, I would immediately check each one for fruit. If I found apples on the left tree, it would naturally assume that it was the apple tree, and vice-versa. Likewise, if we possess the fruits of the Spirit, that is an indication that the Holy Ghost is at work in our lives.

It makes sense, though, that if love, joy, peace, long-suffering, gentleness, goodness, faith, meekness, and temperance indicate the presence of God in our lives, that things such as hate, sorrow, fear, impatience, harshness, dishonesty, doubt, haughtiness, and lack of self control would indicate His absence.

The fruit of the Spirit is necessary in each of our lives. If we desire to be "neither...barren nor unfruitful in the knowledge of our Lord Jesus Christ." (II Peter 1:8), then we ought to bear the fruit of the Spirit, not in moderation, but in abundance.

"Herein is my Father glorified, that ye bear much fruit; so shall ye be my disciples."

                            -John 15:8