Foundational to having a heart for God is to simply believe in God and his way of salvation in Jesus Christ.  Hebrews 11:6 reminds us that those who draw near to God and would please him must believe that he exists.  And Romans 10:9-10 tells us we must believe in our hearts that God raised Jesus from the dead – which implies that we believe he died too.  As I Corinthians 15:3-4 tells us the summary of the gospel is that Jesus died for sins, was buried, and rose on the third day.  Believing in God and in Jesus as our Savior is the first step to having a heart for him.