"Whosoever shall confess that Jesus is the Son of God, God dwelleth in him, and he in God." 1 John 4:15
The scriptures are very clear that salvation comes through Christ Jesus and Him only. Works of any sort will always fall short because no merit man does is good enough to satisfy God the Holy and Righteous. God will only accept perfection and man falls well short in anything they try to do except through Christ. God reminds us through John here that confessing the Son (Jesus Christ) is proof that the Holy Spirit dwells in you. However, it is not as simple as some have made it out to be, for the Holy Spirit to dwell in you means He must have come in to start with. It is evident that the Holy Spirit does not enter every heart because not everyone is saved, and some will never be saved. Some would have us to understand that salvation is a choice or decision on our part but the scriptures prove much different. Paul in the book of Romans says, "For as many as are led by the Spirit of God, they are the sons of God." Romans 8:14 Paul leaves no room for error here; he leaves no room to accept or to deny the Holy Spirit. Let us use this thought here, if the Holy Spirit enters a person's heart and that person decided they did not want to accept Christ and be saved then they have just denied God's will for them to be saved, and beloved that is imposable. God never fails, whatever He wants that He gets. Paul said, "as many are led...they are the sons of God" Salvation is not as simple as believing it entails the work of God and not just one part but the entire Godhead. This is why Paul told young Titus "God is our Saviour" three times. First, the Father had before the world gave to the Son a remnant and made a contract with the Son that His death as the Son of man was required and the Father accepted this payment. Second, the Son died to pay for sin as a payment in full. Third, the Holy Spirit enters a person's heart, walks them to Christ, leads them to believe, and remains in their heart the rest of their life on this earth. This brings us back to Romans 8:14 "as many as are led...are" There is no room for maybe or for rejection because there is no choice on man's end. With all this being said we must conclude as Paul did in Ephesians 1:4 - 5 " According as he hath chosen us in him before the foundation of the world, that we should be holy and without blame before him in love: (5.) Having predestinated us unto the adoption of children by Jesus Christ to himself, according to the good pleasure of his will,". Making salvation as Jonah shouted in Jonah 2:9 "...that I have vowed. Salvation is of the LORD." This is the blessing here that the Spirit of God never leaves, once He enters a person's heart and saves them then He never leaves. God dwells in you, and for the rest of your days. Therefore, while some days may seem that you are alone please remember that you are not, God is in your heart. John reminds us that "No man hath seen God at any time. If we love one another, God dwelleth in us, and his love is perfected in us." 1 John 4:12 that if God dwells in us we should love one another because God is love. This is evidence that God is there in our hearts. Our works will be to bless God and not as a merit for salvation. As James told us, we will show our faith, our heart, the Holy Spirit in us by our works. Faith in Christ is nothing without the Holy Spirit dwelling in our hearts. However, where the Holy Spirit dwells there is faith in Christ, love for God and the brethren, and works that blesses God and not us.