Your relationship with God is secure because, through Christ, you are forgiven and accepted by God. However, God also desires for you to walk closely with Him and communicate with Him throughout each day. Sin keeps us all from experiencing God's love.
Sin is more than cheating, lying, immoral behaviour, etc.
These actions are only the results of an attitude of sin. All of us, therefore, need to experience God's forgiveness for our attitudes and actions. The basis for God's love and forgiveness. For Christ died for sins once for all, the righteous for the unrighteous, to bring you to God. Christ's death is the basis for forgiveness to bring us into a proper relationship with God.