The central theme of Biblical Theology, is the Kingdom of God, not the Gospel, as some assert.  The Gospel is a means to an end that God has foreordained, which is shown in the verses below, which show that the Kingdom of God is God's main objective, and the means to that end is the Gospel of Christ "one must be born again to enter the Kingdom of God.  Many focus only on the "born again part of this verse, but it is the Kingdom of God that is the main subject. 
The order is as follows:

1.The Gospel, which is "Christ died for our sins", "that he was buried", "that he was raised on the third day"

2. The Gospel is the means to Gods end purpose, which is stated below as "so that God may be all in all".
 

"Now I make known to you, brethren, the gospel which I preached to you, which also you received, in which also you stand, by which also you are saved, if you hold fast the word which I preached to you, unless you believed in vain.

For I delivered to you as of first importance what I also received, that Christ died for our sins according to the Scriptures, and that He was buried, and that He was raised on the third day according to the Scriptures...

For He must reign until He has put all His enemies under His feet. The last enemy that will be abolished is death. For He has put all things in subjection under His feet. But when He says, “All things are put in subjection,” it is evident that He is excepted who put all things in subjection to Him. When all things are subjected to Him, then the Son Himself also will be subjected to the One who subjected all things to Him, so that God may be all in all."  1 Corinthians 15