Once saved always saved.
Well if you are born again and convicted of your past sin's already then you should not want to live in iniquity any more.If you join a church and participate in the communion and still are living in sin and iniquity then you are deceiving yourself.Sin is one thing and iniquity is another define the difference.Yes we are all sinners and do sin each day, but don't just do it willingly.Willingly is iniquity.Each sin carries a conviction if you belong to the lord you will know you done wrong and will ask his forgiveness daily.Even a bad thought is sin so we are to pray and beg for forgiveness daily(die daily)at least one time a day to the lord in prayer.If you are doing this you should never fail.