But he who endures to the end shall be saved. – Matthew 24:13

The Holy Ghost acts in the heart as the Spirit of preservation. Where He dwells men do not go back unto perdition. He works in them a watchfulness against temptation day by day. He works in them to wrestle against sin. Rather than sin a believer would die ten thousand deaths. He works in believers union to Christ, which is the source and guarantee of acceptable fruitfulness. He creates in the saints those holy things which glorify God, and bless the sons of men. All true fruit is the fruit of the Spirit. Every true prayer must be “praying in the Holy Ghost.” He helpeth our infirmities in prayer. Even the hearing of the Word of the Lord is of the Spirit, for John says, “I was in the Spirit on the Lord’s day, and heard behind me a great voice.” Everything that comes of the man, or is kept alive in the man, is first infused and then sustained and perfected of the Spirit. “It is the Spirit that quickeneth; the flesh profiteth nothing.” We never go an inch towards heaven in any other power than that of the Holy Ghost. We do not even stand fast and remain steadfast except as we are upheld by the Holy Spirit… He is the garrison of God within our redeemed humanity, and He will keep us to the end. “May the peace of God, which passeth all understanding, keep your hearts and minds through Christ Jesus.” For preservation, then, we look to the Holy Spirit. ~ C.H. Spurgeon

https://www.blueletterbible.org/Comm/spurgeon_charles/sermons/2200.cfm