How can I assist my addicted son to turn his life around?

I can understand how anxious you must feel for your son and his welfare.  You don’t mention his age so I will assume he is an adult for the purpose of this reply.  Whilst returning to his faith would be a necessary part of your son’s recovery, when he is in the throes of addiction he can actually be powerless to do this without professional help.  One way to address your son’s addiction is to wait until he is at a point where he asks for help.  This can take a long time, during which he could find himself in trouble with his health, his relationships and the law.  

There is another option – family or Christian intervention:

Are there other family members or close friends who feel the same way as you do and would be willing to take part in an intervention?  For this you would be wise to employ the services of a professional interventionist, as it is a complex process to carry out involving several steps, and needs to be done properly in order to avoid doing more harm than good.  An alternative is the Christian intervention, involving members of the Christian community you belong to and that your son was previously in relationship with, and your pastor.  The objective of an intervention is to lovingly break through the wall of denial so that the addict realises the extent of his addiction and it’s consequences and consents to entering a rehabilitation program, and this obviously takes planning and much forethought.

There is information on the Choose Help website about preparing for intervention and writing an intervention letter, here: http://www.choosehelp.com/topics/intervention.

I wish you all the best with this and my prayer is that your son will consent to enter treatment.