A more detailed look at both the assurance and warning passages in the Bible
Each of these two schools of thought, the people who emphasise assurance and those who emphasise warning, tend to focus only on the verses which support their view. They often ignore anything that doesn't suit them. There is something about human nature which causes us to zoom in on what we agree with and to ignore those things which contradict us or which make our position more complicated.
However, I would like to suggest that the right approach is to take seriously both the assurance passages and the warning passages. Both are true. They each need to be believed and understood in their proper context and then held, side by side, in a healthy tension. Let's now look at each position again and try to define them more clearly. Let's also look at how they can, and must, be fitted alongside each other simultaneously:
Assurance of salvation
When I first started out as a Christian it was really important to me to find reassurance that I had got eternal life. I wanted to be certain that I wasn't going to lose it due to my own failure to stay the course, or by not being faithful enough to Jesus. I had a deep fear of God's judgment and of going to the Lake of Fire. So, I wanted to be able to know, not just to hope, that I would never go there. Even the thought of one day going to the Lake of Fire horrified me. It should horrify all of us.
So, to someone like me, the various assurance passages were of great importance. I underlined and memorised them. I also felt that, as a matter of logic, if I had 'eternal' life now, then how could it come to an end for any reason? It seemed to be a contradiction in terms for something which, at the moment, is classed as 'eternal' to be able to come to an end at all, for any reason. Likewise, if I was already justified, how could I cease to be so?
Surely, if the promise of 'eternal'. life meant anything, it seemed to me, logically, that it must be permanent. I also felt it ought not to be dependent on my ongoing faithfulness and avoidance of sin However, I still wondered, what would happen if I did sin in a major way? What if I was to let Jesus down or even deny Him under pressure? Would I then be lost? Would I cease to be forgiven and justified? If so, then it seemed to me that I would surely be walking on thin ice throughout my whole life, hoping not to let Him down or lose His approval, but always wondering whether I would.
However, even as a new believer, I understood the gospel well enough to know that that isn't how God operates. I knew that my going to Heaven was not dependent on my complete avoidance of sin, at all times, because that would be impossible anyway. I knew that if I was justified and forgiven at all, it was because Jesus had died for me, in my place, not because of me constantly avoiding or reducing sin in my life. I could see that such an obligation, if it was true, would make me responsible for my own salvation. I would be like a hamster on a wheel, always afraid to stop working in case I lost my eternal life.
So, the assurance passages really helped me personally. They are in the Bible largely for the benefit of people who are sincere and anxious for reassurance. They are most meaningful to those who have a strong sense of the fear of the Lord. For such people, these assurance passages are a precious source of comfort.