we have more than one similar case in our family, so I felt moved to
pray for your grandson immediately after I read your request. (Also,
your grandson shares my name, which pushed me even more...).
First of all while praying I felt like I have to tell you to be
assured that the life of Joshua is in Gods hands. No evil spirit is
allowed or able to take it away from him. Trust God that he is in
total control even if it does not look like like that. He IS protected
by the blood of Jesus which you can always pray over him. Proclaim the
victory of Jesus over the life Joshua - even celebrate his redemption.
This may drive evil forces mad and the situation may even worsen
before there is a breakthrough. Simply be ready for that and stand
firm in your faith and put ALL your trust in God!
Second, from my personal experience: Feed Joshuah with the word of
God! Feed him with comforting scripture. Feed him with scripture
telling him that God truly loves and CARES about him. Even if he
resists and counterparts it, feed him, feed him, FEED HIM! It
certainly helps! It moves his spirit and breaks down the strongholds
of the enemy! Maybe he is able and interested in some books like e.g.
"The cross and the Switchblade" from David Wilkerson: