Will Be Saved Or Will Not Be Saved?, Faith Questions Options

[Janet]

Hi, my sister used to be a Christian. At one point, she went on short missionary trips
to spread the Good News. But a few days ago, she told me that she did not believe
in Jesus Christ any more for some reasons. Since she lost her faith, will she still
go to heaven when she dies? Also, what happens to someone that believed in Christ
but continue to sin on Earth, when he/she dies, will the person get punishment from
God in heaven? Please advise, thanks.