Why were the Gospels written?

In his excellent book, Four Portraits, One Jesus, Mark Staruss lists 7 reasons which motivated the Gospel writers to write down the story of Jesus:

1. Historical: the need for a faithful and authoritative record of the words and deeds of Jesus.

2. Catechetical: the need to instruct converts in the Christian faith.

3. Liturgical: the need for worship material in the church.

4. Exhortatory: to encourage and assure believers in their faith.

5. Theological: the need to settle internal disputes.

6. Apologetic: the need to respond to external attacks on the church.

7. Evangelistic: the need to call people to faith in Jesus.

In other words the Gosples exists to have a presence in each aspect of our personal and church life. They want to instruct us in what Christianity is and in what it means to be a Christian. On reflection it seems that this is far from reality in many modern churches and for many Christians. I think this is to the detriment of Christianity and goes against the intent of the Bible.

To put it another way, in striving to be Gospel people, what role do the actual Gospels play in that pursuit?