If someone puts their faith in Jesus as their saviour, are they saved for evermore regardless of what follows?
Our Apostle Paul says >
"we" "who first trusted in Christ," in Ephesians 1:12. So, yes in getting saved and born again, a person trusts in Jesus. And the believing which Jesus means brings trusting and obeying. So, Jesus and Paul and our other New Testament writers mean the same thing.
Trusting Jesus brings a person to obey Jesus. So, if by "regardless of what happens" you mean a person does not change, this is not trusting in Christ.
And obeying includes how we submit to our Father in His peace >
"And let the peace of God rule in your hearts, to which also you were called in one body; and be thankful." (Colossians 3:15)
This is part of our basic Christian calling >
"in one body", Paul says, here.
And Jesus Himself has said, in calling to
"all" >
"'Come to Me, all you who labor and are heavy laden, and I will give you rest. Take My yoke upon you and learn from Me, for I am gentle and lowly in heart, and you will find rest for your souls.'" (Matthew 11;28-30)
So, Paul says we all are
"called in one body" to submit to how our Father rules us in His peace. And Jesus calls to
"all" to submit to His
"yoke" so we have
"rest for your souls." So, I can see that the two mean the same thing.
And will you feel living in God's peace which gives your soul rest? Yes. Will you feel and experience submitting to the
"yoke" of Jesus which has you finding rest for your soul? Yes - - - if you live in God's peace with rest for your soul, you will feel this.
But this includes the process of refusing to give in to anti-love things, and living in God's family caring and sharing love, instead >
"Let all bitterness, wrath, anger, clamor, and evil speaking be put away from you, with all malice. And be kind to one another, tenderhearted, forgiving one another, even as God in Christ forgave you." (Ephesians 4:31-32)
So, by the way, this comes in sharing with other children of God . . . not in isolation with your own do-it-yourself stuff!! We help one another to get real correction and love's perfection in sharing with God and one another.
As far as I know, you feel things like bitterness and unforgiveness; and if you reject these things and live in God's peace which is immune to anti-love feelings and emotions, you will feel how you are because of not submitting to Satanic things messing with you. In God's peace with almighty immunity, you will feel being peaceful while you are being
"kind" and
"tenderhearted" and all-loving and generously forgiving
"even as God in Christ forgave you."
Now there are people who claim how God has forgiven them for all sins "past, present, and future", and they say how God loves them "unconditionally", but then they say they will go to Heaven, no matter how they sin or even commit murder just before they die.
Well, if the day of judgment will be in Heaven, yes everyone will go to Heaven, but then will they all stay with Jesus??
And yes God loves us unconditionally, but this is our example required of us, so we likewise forgive "even as God". And Jesus says if we do not forgive, what will happen? > Mark 11:25. As God's children we live with God in His love which has us also being generously forgiving and unconditionally loving. Or else a person is not a child of this love.
And every person who is saved is a child of God who has this love living "in our hearts" >
"Now hope does not disappoint, because the love of God has been poured out in our hearts by the Holy Spirit who was given to us." (Romans 5:5)
This love is God's own love in the Holy Spirit > Heaven's love in Heaven's Spirit, having Heaven's beauty and quality of pleasant rest and personal sharing with God and one another as His family. So, yes, we do feel this.
But Satan and his spirit feel horrible > his unforgiveness, frustration, lust for pleasure, anger and rage, boredom and loneliness, bitterness, arguing and complaining feel horrible and are so terribly degrading and anti-love. This is why people in Satan's kingdom are so desperate to feel pleasures > because they are trying to make themselves feel something nicer than their deep-down awful-mess of sin.
So Jesus has compassion for us. He does not want us to keep feeling and suffering in Satanic stuff. So, He calls "all" who are laboring and weary in sin, "and I will give you rest," He guarantees > Matthew 11:28-30.