Yes, the Gospel is replete with the fact it is all of Christ. All of salvation is from God, every aspect so all the glory is due to him;
1 Corinthians 1:26-31.
Yet, there is still the call to self-examination as well
(2 Corinthians 13:5) and warnings to not be deceived. Whether or not one is truly converted is the concern and basis for these warnings. That said, we better be inspecting our own fruit, this Paul calls us to;
1 Corinthians 6:9-11, Galatians 5:19ff, Ephesians 5:5, Galatians 6:1-8, and of the
epistle's of John, Peter's epistles, warnings from
Christ and other
Scriptures from Paul.
We shouldn't mitigate sin in the professing believers life when it is a lifestyle and relegate it to
"If they don't stop God will kill them." That's a terrible presumption to make and no person needs assured of conversion in such a state, they should speak to a pastor and take a close look at the transforming power of the Gospel unto
all who are converted;
2 Corinthians 3:17ff. It could be that the person is not truly converted.
We are all fully aware of the arguments concerning the practice and or lifestyle of sin and typically it is stated something like this;
"If you sin everyday then you're practicing sin too, so let's dismiss the warnings!" This excuse is used to curtail the solemn warnings and doesn't take into account the seriousness of the warnings, it is instead entirely dismissive.
Washing our feet daily due to falling short is not a lifestyle or practice of sin, and daily repentance, asking forgiveness to me is evidence of conversion;
1 John 1:8-10. Practice of sin is to set up shop to sin
(1 John) it is the lifestyle of the person, and the topic needs needs further understanding and examination.
1 John 5:13 is written only to those who pass the tests of conversion throughout the epistle yet many are ruched to that verse, out of context, to assure them of salvation. It is not a proof text for believe-ism though that is how it is often misused. Telling a person they are guaranteed heaven at the moment they make a profession of faith is unfortunate, we do not know if that person is truly converted at all. Telling them
"No matter what!" sends a signal to the unconverted and they will go on in sin and finally are found to be dogs or swine, not sheep;
2 Peter 2:22.
We should be aware that discipline from God is also evidence of conversion, and, that receiving no discipline shows the persons to be bastards, not sons. We should look at this as evidence as well, that is the sense of the warning and encouragement, unconverted or converted respectively.
There are plenty of professing believers who are not transformed, live and practice sin who are assured they are going to heaven when they die because at VBS or some other event they made a public profession of faith and it ended there.
Now, if a persons life is being transformed, there is now a love for God, for his Word, a repentant attitude toward sin, love of the brothers, transforming growth, obedience to Christ, cleansing from the guilt of sin, understanding and revelation of who Christ is &c then give all the glory to God for his salvation working in you!