I recently discussed with a dear brother the question of whether God needs us, his position was perfectly reasonable and understandable in viewing such an idea as presumptious in the extreme to suggest that He does, but I took a different stand and here is the reason I gave to suggest that God does need us.
Jesus has told us that we are held securely in Father's hand and nobody (not even ourselves) can take us out of His hand, He has covenanted with us to "never leave us nor forsake us"
If it were at all possible that any one of us who have trusted ourselves to Christ for the eternal well-being of our souls should fall and lose our share in the everlasting life that God has promised to each and every one of us then His oath and His covenant will have failed, the devil will have gained a great victory over God, this will never happen, when Christ is presented with His bride there would be a spot and a wrinkle, if it were possible that some had failed to attain what God has promised to them.
Eternal security does not depend upon who or what we are or what we can or cannot achieve, it depends (God Himself has made it depend) entirely upon the promise of God and His ability to perform and deliver on His promise. Be assured He is well able to do so. Therefore on this basis He does need us, His oath and His honour He has made to depend upon our preservation.
But why did He make it to depend thus? it is quite clear that if our eternal welfare were to depend in the tiniest degree upon ourselves, what we are in ourselves or what we can achieve then would our souls be forfeit indeed. And the only reason I can suggest for His arranging matters so is (I say hushedly) because He needs us.