For some reason the android:textColor only seems to update the title color. You can change the message text color by using a
SpannableString.AlertDialog.Builder builder = new AlertDialog.Builder(new ContextThemeWrapper(this, R.style.MyDialogTheme));
AlertDialog dialog = builder.create();
Spannable wordtoSpan = new SpannableString("I know just how to whisper, And I know just how to cry,I know just where to find the answers");
wordtoSpan.setSpan(new ForegroundColorSpan(Color.BLUE), 15, 30, Spannable.SPAN_EXCLUSIVE_EXCLUSIVE);
dialog.setMessage(wordtoSpan);
dialog.show();