What does it mean,to endure to the end?What did those people do to fall away?
You are what you are. There is nothing you can do to change who you are. Those people loved darkness more than light. They showed their true colors.
If you are following God now, but later decide that you don't want to anymore, there is nothing you can do NOW to change your future decision. What you are will come to light at some point. Just be the best you can be, hope in God's love and mercy and hope that you are one of the good guys.
If you have a desire for God, you will be with God. When you lose the desire for God, you won't want to be..you won't care then.
Becoming a Christian in order to escape hell is kind of a wrong intent. Becoming a Christian should be because you BELIEVE in the lifestyle that Jesus taught. It should be because you WANT God. If you believe only because you are scared of the bad punishment, you might be one of the ones who later decide to fall away.
Faith is a delicate thing. It changes. As new information comes, your views and beliefs about God might change. For example, God told me that there is no hell, so I don't believe it anymore. And if you ask: well, what incentive is there then to try to be good, to serve God? Well, the incentive should be that you want to please God out of love, not out of fear. And the incentive should be that God's desires should become your desires as you draw closer to Him in your relationship with Him. You would want the same things He would want...
And if we fall short of being what we believe God wants us to be, there is always grace. That's why it's there. God knew in advance that we would fall short. It's no big deal. As long as the desire to be good is there, as long as you keep trying and keep growing, you are under the grace.
We should stop hoping in our own ability to secure our future. We should start blindly and with all heart trusting God to do it for us. But of course, before we can do that, we have to learn to trust him. And that comes from knowing Him personally and intimately.