Every matter has many sides to it, but it is one defect of our fallen nature to give importance to one or two aspects of a matter and overlook the others. An example is when someone falls in love with another, and becomes 'blind' to the faults of the other. When it comes to theology, if we exaggerate any part of the truth to the extent that we ignore others, we end up with a caricature of the reality.
For example, because of the unbalanced preaching of the Gospel these days, many people think of God as being love and imagine that the God of the OT is different from that of the NT. This cannot be true (Jn.14:9;10:30). If only we piece together observations of God from all over the Bible, we can see that He is not only love, but also holy, righteous, just, impartial, sovereign, etc. How He behaves in different situations will depend on what is suitable for each situation. He will show mercy to those who repent, but judgment to those who refuse to repent (Ro.11:22).
We need the full Bible to get the big picture of God. If anyone emphasises one aspect of God above others, when it comes to other parts of the Bible that seem to contradict it, they will have to twist words or redefine terminology.
Some people exaggerate the sovereignty of God and find no place for the free will of man. They pick out verses that seem to support this view. But then there are also many other verses that talk about the responsibility of man to choose the right thing and the rewards and punishments that come depending on what we do. The solution is to place all the Bible together and understand that in His sovereignty, He has created man with a certain limited domain within which he is free to make choices. If we look only at God's sovereignty, we have to come to a God who is unpredictable, who is arbitrary in what He does, and who ultimately becomes responsible for all the evil there is in the world! This is a complete misrepresentation of God.
Another example is hyper-grace, where the grace of God is exaggerated to such an extent that there is nothing else that a Christian needs to consider. Fear of God, repentance, confession of sins, denying oneself, obedience to God, etc., seem to become unnecessary and irrelevant to those who come under grace. Yes, the undeserved favour of God is so unimaginably beyond our mind that we get overwhelmed even thinking about it. In one sense we can say that we cannot really exaggerate it. But the problem is that the NT is also full of things God wants us to do, warnings we need to take heed not to fall from grace, and exhortations to help us to keep moving forward. Once when I was talking to a hyper-grace follower, I said that if we followed the hyper-grace teaching we would have to ignore large portions of the New Testament, and he agreed with me! Surprisingly, even that recognition did not turn him away from his conviction!
One mark of growing in maturity is becoming more balanced.