What Grace777 and mailmandan said are true.
When people believe they can keep their salvation by their own maintenance, it is because they have a low view of sin, they think sin is what you do, when it's what you do, what you think of doing and what they are. So no one can stay saved, without confessing every second, because the standard is to be perfect like your heavenly Father is perfect, so we fail every second that we live. That is why it is Christ's perfection that is imputed to us, that we can be saved and stay saved. Not by any works of righteousness, so that we can boast or I'm saved because of my faith and I'm keeping it, noting we do saves us or keeps us saved.
Once the Spirit has infused us into Christ we can not unfuse us from Christ, it is called our union with Christ, the adoption, sealing of the Spirit, our justification. Roman law as USA law, if you adopt a child, in Rome you could also adopt adults. You have to leave them an inheritance, you can write off your own children, as the Father did with Christ, so that we could be adopted. Your nature children can not do anything to get part of your inheritance if you do not leave them anything, but an adopted child can and will get it because of the law. The whole world may be children of God, because he created all, but they do not have a right to an inheritance if He so choses not to leave them one, but we as adopted children have every right too an inheritance, which is our blessed hope our glorified bodies.
We are so close to Christ that when Saul was persecuting the Church, Jesus said to him Saul, Saul why are you persecute me? Jesus did not say, Saul, Saul why are you persecuting my Church. We are so bonded with Christ that if we have illicit sex, we have joined Christ to that person as will as we are joined to them. There is something very special and mythical for leak of a better term. When two people have sex, they become one, weather married or not II Corinthians 6:15-16 Do you not know that your bodies are members of Christ? Shall I then take the members of Christ and make them members of a prostitute? Never!16 Or do you not know that he who is joined to a prostitute becomes one body with her? For, as it is written, “The two will become one flesh.”
Once you are joined to Christ you are joined together with Him for ever, in the same way that once you have sex with someone you are one for as long as you live, maybe longer I don't know. There is a reason why all of our salvation is like a near eastern marriage, the father choses the bride for the son, as Abraham did for Isaac. The son does not know when he is going to go get his bride as jesus do not know when He will come for His bride, only the Father knows. And just as the two become one in a marriage, so we become one with Christ in our union with Him, when the father make us alive in Him and raises us with Christ and seats us in heavenly places. There is another thing, why would the Father see us in heavenly palaces if two minutes before I die I lose my salvation? It can not happen or the Father would not say by the Spirit that He set us in heaven already.
So no one could be saved if it depended on us, yes Jesus said lots of things that are demands to maintain a right standing before the Father, He did not say them because He thought you could keep them, He said them to the Jews so they could see that they could not keep them and rely on His grace, not their works. Jesus said many things that are needed to keep ones salvation if you are keeping your salvation by works of the Law. The Law is the foundation of Christ, to bring us to the knowledge of sin Romans 3:19-20, once we see that we could never keep the Law top maintain our salvation, we rely on His grace to keep us saved.