"You can't accept Jesus and trully love him and then commit a serious sin. If you do sin afterwards, then your acceptance of Jesus was a lie."
Do you mean like David when he kill Uriah or Peter when he denied The Lord three times or Mark when he became so self-occupied that he quit the mission field with Paul and Barnabus and went home to mummy, yes I can see their acceptance was a lie, no need to look for them in Heaven.