As a pastor, there are some questions about life-matters that come in quite regularly. I was recently asked one of those common questions that I have actually gotten a few times over the years. The question goes something like this: I know a family who is struggling with a loved one who has memory problems. The person is not who he/she once was (and, in some cases, the person's personality can completely change). What does the Bible say about these types of issues? Can my loved one still be saved, even if they do not have an active faith anymore? Are there any Bible verses I can read to get any help?
This is certainly a big issue. More and more families are facing these diseases associated with memory loss. I am persuaded that these are the worst types of diseases, and sometimes they can persist for many years. As big of an issue as this is, there are many conversations that need to be had, but maybe I can provide a brief response here to put us on the right path for our thinking on the subject.
The first thought that comes to mind is the narrative about Abraham's dialogue with the Lord in Genesis 18. In verse 25 he affirms that the judge of all the earth will surely do what is right. We certainly trust that God will always do what is right in the end. We can never doubt that, not even for a moment. We cannot entertain for a second that God may do wrong. He is just and holy in all His ways. He WILL do what is right (and what is not right now will be settled on the Last Day). Those with dementia/alzheimer's/etc., in my opinion, will not be held accountable for their actions during that period of time with the disease, like others would who have full mental health.
Finding a particular chapter and verse that would serve as a proof-text would be difficult for this or any number of things. There are many issues in life in which we must think through the situations and respond to them with theological answers informed by what we know about the God of the Bible. We know a lot about God from His special revelation in the Scriptures, and some of those things are that God is, of course, loving, compassionate, gracious, and always does what is right. So, take heart! Trust the God of the Bible on this subject and every other!