I think the main reason why saved believers in Jesus do not grow spiritually–why they do not follow the Holy Spirit within them, why they do not grow in faith and sanctification, is that, first of all, they are not assured of their salvation.
They do not know about or believe in eternal security.
They do not see clearly the pitfalls of Lordship Salvation teaching, even if they are saved, which puts them under constant fear of not being saved.
People are not motivated to live in grace and they cannot really grow spiritually if they’re constantly being threatened with the loss of their salvation, or threatened with the idea that they aren’t really saved at all.
To grow spiritually, people must live in the gracious loving presence of the Lord.
The indwelling Holy Spirit is with us and in us as believers, but there is an element of will.
There is the influence of the Holy Spirit toward believing in our holy, perfect and loving identity in Christ, following the Holy Spirit, living in God’s love, trusting God, and knowing and abiding in the words of Jesus.
Without these things, you will not grow spiritually.
With these things, you will grow spiritually.