The issue is not salvation or sin but vigilance and worldliness. If we, as Christians, become enraptured and molded by the world, occupying ourselves with it rather than with Christ, the Lord might just shut the Rapture Door on us. This is not a loss of salvation as much as it is a loss of privilege.
Do you have a Bible reference to back that up? I’ve got one. “For I am confident of this very thing, that He who began a good work in you will perfect it until the day of Christ Jesus.” (Phil. 1:6)