At the heart of Christianity is the Gospel. In fact, the case could be made that Christianity is the gospel. The Gospel is the truth about God and his acts, as revealed in Jesus, the divine Word. If we are to respond in faith and obedience, we must have an intricate understanding of who God is (faith) and what He does (obedience).
As James says, faith without works is dead. What you truly believe will shine in your actions. So an understanding of the Gospel is not only of what your heart is to think, but what your hand is to accomplish. We are not only to think God’s thoughts after Him, but also to do God’s deeds after Him.
Jesus preached, “Repent, for the kingdom of heaven is at hand!” When he sent His disciples into the surrounding towns, Christ commanded, “Proclaim as you go, ‘The kingdom of heaven is at hand!'” And, “It is enough for the disciple to be like his teacher, and the servant like His master. Paul exhorts, “Husbands, love your wives as Christ loved the church.”
You see, the actions of God are our pattern for action on earth. And the heart of the actions and character of God is the Gospel.