I don't believe that sin causes us to lose our salvation. Sin is serious, there are consequences for our sin, and God will discipline us because He loves us enough to want us to change, but a Christian has a whole new relationship to sin. Take for example, your relationship with your earthly father. If you disobey him, you are not a good daughter. If you rebel against him, you cause him much pain.
Nothing can change that fact.
Likewise, if you truly have given your life to Christ, then you are born of God. You have a heavenly Father. Nothing can change that. For more see What Sin Does and Doesn't Do in the Life of a Christian . I'm about to say as a statement about your parents.