Converting to Judaism or Islam vs Trinitarian or Uniterian If a Christian "converts" to Judaism or Islam (or any of the Abrahamic religions), is he still considered saved as a Christian?  What if he/she converted from Trinitarian to Uniterian?  This is a general Christian question, so I am requesting an overview of Christian positions on such conversions.
There is no consensus among Christians on this question.  Assuming that the conversion is genuine and permanent, rather than momentary weakness, the three main schools of thought that apply to this issue are:

Conditional Security

According to this view, Christians can lose their salvation.  Thus, a Christian who converted to another religion would be seen to have lost his salvation, if he had it in the first place.  Christians who hold this view, such as Arminians, would answer "No".  

Perseverance of the Saints

Another school of thought is that Christians cannot lose their salvation, and that true believers will persevere till the end.  According to this view, although true believers may fall and stumble temporarily, they will never fall away permanently.  A supposed Christian who permanently converted would be seen as having never been a genuine Christian in the first place.  Like the first view, Christians who hold this view would answer "No".

Free Grace Theology

Free Grace Theology is a view in which Christians cannot lose their salvation, and may fall away permanently.  This view teaches that the saved may or may not become disciples, and may or may not undergo the process of sanctification.  Christians may believe in Christ at one point, and subsequently forsake any identity with Christianity.  Christians who hold this view would answer "Yes".