Paul gives us the answer: to make us praise the glory of his grace.
It is interesting to note that in Matthews version of the gospel, the first mention of the paternity of God comes from Jesus in the sermon on the mount. No one lights a lamp and put it under a tub; they put it on a lamp stand where it shines for everyone in the house. In the same way your light must shine in the sight of men, so that, seeing your good works, they may give glory to your Father in heaven.
Two things to take note here. First is when Jesus revealed the paternity of God, he talked about giving glory to the Father in heaven. It is as if he were saying, this is the first thing that you must know about your relationship with your Father to give glory to him.
Second, he presents God as YOUR Father not my Father. If you read the whole sermon on the mount, Jesus used the phrase your Father twelve times. He mentioned Our Father once and my Father once.
This is as if to stress that God is first of all, a Father and he is our Father yours and mine! More importantly to you - he is YOUR Father.
