God never leaves anyone but He doesn’t necessarily dwell in them, especially if they do not believe in Him.
Romans 8: But you are not in the flesh, you are in the Spirit, if in fact the Spirit of God dwells in you. Any one who does not have the Spirit of Christ does not belong to him.
10 But if Christ is in you, although your bodies are dead because of sin, your spirits are alive because of righteousness.
11 If the Spirit of him who raised Jesus from the dead dwells in you, he who raised Christ Jesus from the dead will give life to your mortal bodies also through his Spirit which dwells in you.
If you die never accepting Jesus or if you have accepted him and then rejected him, God allows you to descend to hell by your own choosing. You choose to separate yourself from God. You, in a sense, leave God.
Also, there are believers who are deceived. They think they love God and have accepted Him, but they haven’t.
1 John 4 “God is love, and whoever remains in love remains in God and God in him. In this is love brought to perfection among us, that we have confidence on the day of judgement because as he is, so are we in this world. There is no fear in love, but perfect love drives out fear because fear has to do with punishment, and so one who fears is not yet perfect in love. We love because he first loved us. If anyone says, “I love God,” but hates his brother, he is a liar; for whoever does not love a brother whom he has seen cannot love God whom he has not seen. This is the commandment we have from him: whoever loves God must also love his brother.”
St. John goes on to recognize that some sin is considered deadly (what Catholics call mortal sin). It completely separates you from the love of God until you confess it contritely.
1 John 5: 16-17 He writes, "If anyone sees his brother sinning, if the sin is not deadly, he should pray to God and he will give him life. This is only for those whose sin is not deadly. There is such a thing as deadly sin, about which I do not say that you should pray. All wrongdoing is sin, but there is sin that is not deadly.
Protestants get it wrong all the time. They think if you accept Jesus as your savior, that you are saved just by that profession of faith. It is a good start, but more is needed. You must live the Christian life and reject sin. St. Paul says, “Work out your salvation in fear and trembling.” Philippians 2:12
St. James says, “Faith without works is dead.” James 2:26.
St. Peter says, "Rid yourselves of all malice and all deceit, insincerity, envy and all slander, like newborn infants, long for pure spiritual milk, so that through it you may grow into salvation for you have tasted that the Lord is good. 1 Peter 2:1-2.
Even St. John says that the dead will be judged according to their deeds. He writes, "I saw the dead, the great and the lowly, standing before the throne, and scrolls were opened. Then another scroll was opened, the book of life. The dead were judged according to their deeds, by what was written in the scrolls. Revelation 20: 12
Jesus even warns those who think they know him that some will be damned eternally.
He says, "Not everyone who says to me, “Lord, Lord,’ will enter the kingdom of heaven, but only the one who does the will of my Father in heaven.” Matthew 7:21
As you can see from what Jesus says, some will recognize him as Lord but will not do his Father’s will and therefore they will go to hell. Take heed and do the will of God!
