I pray you & your son know, believe & follow Jesus as Savior from our sins & Lord of all.... With that, here are just some weapons in this warfare to utilize!
1) Pray pray pray
2) Study the Word of God
3) Holy Spirit - every believer has Him dwelling within us. We daily need a fresh infilling for guidance, comfort, strength, wisdom, courage & discernment.
4) Praise - a powerful weapon, especially when praising in a storm of discouragement & lies satan throws.
5) Armor of God - Eph 5 explains each garment including the Sword of the Spirit (only offensive weapon) = the Word of God.
6) Thanksgiving - in ALL circumstances
7) Obedience to Christ
8) Blood of Christ & Word of our testimony - We are overcomers in this life because He has overcome. And our lives are hidden in Christ with God. No enemy or obstacle can touch our souls. When we have been set free by the blood of Christ and the power of His sacrifice by death on the Cross, we have a new identity in Him.
9) Talk to your son with the respect, love & kindness you want from him... as if he were walking with the Lord, one of God's precious children. It's hard, but model it for him & eventually things will improve. It has with me, but it's ongoing process... like our Father above, must be patient with us! God bless you!