Through grace, by Faith in Christ Jesus we're saved, not of course to live a wavering life on a shaky foundation of the word, but to walk steady in Christ Jesus.
Walking steady, is the life Jesus called and restored us into, that we have a firm foundation where He builds His house, because we are His building, we are rooms in the Father's House as He said;
“In My Father’s house are many mansions; if it were not so, I would have told you. I go to prepare a place for you.”
[ John 14:2 ]
We are that building. Our lives lived in God, either in selfishness or in selflessness to God will determine our building, our restoration.
It's not God's will that we remain weak, falling and rising. When in reality, His will is to restore our fallen buildings ( our hearts ), that upon a strong foundation by being filled with the holy spirit becoming more like God, He'll build and restore us. Now Jesus wouldn't want to build upon a shaky foundation, He's so loving not to destroy us with the weight of His glory, because of how less of Him we are and more of flesh.
This foundation is built on the very nature of God being nurtured and overflowing in and through us naturally like breathing, not in struggle, but like breathing. God can only build and restore His glory on a strong foundation, not a foundation still less of Him and more of flesh.
The cause of faltering on this path of life is birthed from; doubt, the deception and denial of the delivery power of God's word to deliver a man completely from sin and death to live a life of holiness in God, naturally.
It is birthed also from our lack in love, selfishness to see Jesus only for what we can get from Him, or to escape hell, rather than loving Him in sacrifice, for that's what He restored us for, a relationship. It is this relationship that'll bring us back to our original place in God.
It's one thing to have the holy spirit when we received Christ, and another to become filled with the holy spirit and then, even greater to become baptized in the holy ghost.
Being filled with the holy spirit is; allowing the holy spirit dominate our heart by feeding on God's word, “His life,” to live naturally in the nature of God.
However, being baptized in the holy ghost isn't necessarily speaking in tongues as many believe, surely that's merely a sign. Being baptized in the holy ghost however, is an empowerment from on high to walk in God's project. Only a few enters into this, because it requires selflessness, a death to self.
Because men cease to follow, they end up being shaky.
“ Whoever has been born of God does not sin, for His seed remains in him; and he cannot sin, because he has been born of God.”
[ I John 3:9 ]
However, For this scripture to become true in our lives, We must have;
Faith, Repentance, Believing and then follow to become unwavering.