but, speaking the truth in love, may grow up in all things into Him who is the head - Christ -"
Ephesians 4:14-15 (NKJV)
Sometimes when there is road construction, or maybe a building is being remodeled, there will be a sign posted somewhere that says that what is being done will make things better. There might be a sign that has a slogan like, "building today for a better tomorrow", or "we are building to make things better for you". Building or changing things in the present to make things better in the future is good. If something is only beneficial now, and it will not be helpful in the future, that thing is not such a good thing.
In Ephesians 4, Paul said that believers need to stop being children who are just tossed around with every wind of doctrine. This means that we should not just follow every teaching that comes along or is popular in the Church world, no matter who says it. But instead, Christians need to speak the truth in love (Ephesians 4:15), be mature in understanding (1 Corinthians 14:20), and desire the Word of God that will cause us to grow (1 Peter 2:2). We need to grow up spiritually today so that we can be stronger, more mature believers tomorrow.
Spiritual growth is important, it is necessary, and it is something that should be happening on a continual basis in the life of a Christian. We should be growing and improving, rather than just being the same person and same type of Christian in five years that we are right now. By spending time in God's Word and following the direction of the Holy Spirit, we can grow and develop spiritually. We need to develop spiritually every day, so that we are more effective members of the Body of Christ, and a better witness to the unsaved world, today and tomorrow.