Since NOBODY makes this claim except as a 'strawman' it is a moot point to the discussion of whether God NEEDS YOUR "help or permission" to save you [Synergysm: mother of salvation by faith and works] or God saves "all by Himself" [Monergism: mother of salvation by faith alone ... and even faith is a gift from God].
Nobody actually advocates: "You are saved ... now go an sin all you want."
Actually, that’s not true.
I have been at these kinds of discussion for 11 years approximately and I listen carefully to what many people say in the Perpetual Belief Alone Salvationism camp. I have talked with people in person and online. I have done extensive research into their stated beliefs and I have traced the origins of this dark doctrine. There are a three major different categories of Perpetual Belief Alone Salvationists.
#1. Hyper Grace.
(Yes, you can Google it and it is a real recognized term amongst Christians).
Hyper Grace = Those believers who believe they can practice sin and still be saved and no amount of sin will keep them from their Savior all because they have a belief alone in Jesus for salvation or in their unbiblical of saying that all you have to do is believe in the finished work of the cross (Which denies the resurrection). It’s also called “Easy Believism.” They can be either be Calvinist (Monergism), or Non-Calvinists (Arminians) (Note: Yes, I can provide proof that some Calvinists hold to Hyper Grace; Just be patient and I will show you this in a little bit). They are for Eternal Security or Once Saved Always Saved.
#2. Partial Hyper Grace (Which is my invented term based on Perpetual Belief Alone Salvationist’s double speaking in saying they are for holy living and they are in support of “not practicing sin” (So as to show the mark of a true believer), and yet they contradict that moral standard by making other kinds of statements at another time by saying that they can sin and still be saved on a smaller level or sinning for a season). Non-Calvinists and Calvinists hold to this viewpoint. Gotquestions (a 4 point Calvinist website) is a perfect example of this double minded nonsense. In one article by them, they say they have serious doubts about a believer being saved if they are not progressively living more holy. Yet, they contradict this moral standard in the same article by also say that a backslidden believer is still saved (i.e. that means that the prodigal son who was living it up with prostitutes was still saved in Luke 15). You can check out that article
here. This is just deceptive. A person can just deceive themselves that they go prodigal their whole life and then get their heart with the Lord toward the end of their life and think they are saved. Partial Hyper Grace Christians have said that a believer who commits suicide is still saved. Partial Hyper Grace Christians believe that if a Christian who generally lived a holy later looks upon a woman in lust and they got hit by a bus and died… they would be saved (Which ignores 1 John 1:9, Proverbs 28:13). They are for Eternal Security or Once Saved Always Saved.
#3. Free Will Baptists.
Free Will Baptists reject Eternal Security or Once Saved Always Saved. They believe the only way you can fall away is by no longer believing in the Bible or God and or in rejecting Jesus as your Savior after you have believed. However, just like the other two camps of Perpetual Belief Alone Salvationism, they believe you can sin and still be saved on some level.
You mention Monergism (Which is Calvinism). This is basically determinism in disguise. Unconditional Election is basically saying God elects based on no conditions whatsoever within the individual. Hence, why it is called Unconditional Election. This means God force saves some people and not others. The problem with this view is if God normally saves by some kind of forced regeneration or salvation, why does He not save them all? By default, God would be the blame for not saving people when He could (Thereby not making Him a loving God who actually cares). That would be like a coast guard saving everyone within a group you were with that was lost at sea, but the coast guard randomly chose to not save you and your family for no good reason. In such a scenario, you would think the coast guard was not being fair. While there are tons of verse that refute Calvinism: 2 Thessalonians 2:10 is really the only verse you need to refute Calvinism. It is basically saying that the reason why those who are perishing is because they are not receiving the love of the truth that they MIGHT be saved. This does not make sense in Calvinism and many Calvinists I have shared this verse with simply either ignore this verse or they attempt to change it somehow because they don’t like what it says plainly. I honestly don’t know how Will Kinney (a KJB Onlyist like myself) twists this verse. Will Kinney is a Calvinist.
There is also High Calvinism (Which is the belief that one does not even have to preach the gospel; God will just lead them to be saved).
Side Note:
I hold to Temporal Belief Alone Salvationism in that one is saved by a belief alone only in their Initial Salvation when they first are saved by God’s grace through faith in Jesus Christ (Which is a process of salvation without works). Yes, I know. Calvinists have claimed that for us to believe in Jesus is also a work, but it is not.