I won't answer questions 1 and 3, but I can discuss question 2. Once you know how I answer #2, you will know how I answer questions 1 and 3.
How will you measure that what you are doing is good enough to keep your salvation?
Jesus said:
6 ... I am the way and the truth and the life. No one comes to the Father except through me.(Jn. 14: 6)You get to the Father through Jesus Christ. That's why Christ calls Himself "the way." And how does Christ become "the way"?
Christ is the way by which we should walk. So if He is the road, you walk along that road. You don't stray outside of the path where the road leads.
And what is this road or path? Christ is talking about following His commandments. You follow His commandments, and you follow the path towards the Father. Very simple, isn't it?
Clearly, therefore, it's your obligation to know what those commandments are. Then it's going to be your obligation to follow those commandments.
So how do you measure if your works are good enough? You measure your works against the commandments of Christ. If you're following His commandments, then you measure up. Otherwise, you don't measure up.
What if you honestly thought that you measured up, but you were in fact mistaken in your estimations? God will decide, not you, because God knows if your mistake was an honest one or not.
Sa Once Saved Always Saved, bakit aalamin mo pa ang commandments ni Kristo? Di ba ligtas ka na kahit ano pa ang gawin mo? Huwag mo nang alamin ang commandments, kasi kahit ano pa ang gawin mo, ligtas ka pa rin.
Meron namang interpretation, may good works din daw, pero automatic daw ang good works na yon pag ligtas ka na. Kung automatic ang good works, hindi na kailangang alamin ang commandments ni Kristo para sumunod sa commandments na iyon. Bakit pa, e kahit ano ang gawin ko, sigurado namang "good" yon kasi automatic nga ang good works pag ligtas ka.
That's how absurd the OSAS doctrine becomes, when the truth of the matter is that following the right path is not only required, it's also very difficult. That is why the bible says:
13 “Enter through the narrow gate. For wide is the gate and broad is the road that leads to destruction, and many enter through it. 14 But small is the gate and narrow the road that leads to life, and only a few find it. (Mt. 7:13-14)It's not going to be an easy thing to do, as if being saved meant that good works come so easily that they arise automatically. In fact, it's going to be a war-like struggle:
11 Put on the full armor of God, so that you can take your stand against the devil’s schemes. 12 For our struggle is not against flesh and blood, but against the rulers, against the authorities, against the powers of this dark world and against the spiritual forces of evil in the heavenly realms. (Eph. 6:11-12) That is how you work out your own salvation. Know Christ's commandments and follow them. Only you can do it for yourself, because you have free will. If you want to do it, well and good; if not, then it's up to you.
Does that mean Christ's sacrifice was useless? Of course not. Whereas without Christ's sacrifice, you won't get to heaven, no matter what you do. With Christ's sacrifice, salvation is now possible, as long as you yourself work and follow His commandments. That's how important Christ's death on the cross was, yet it still doesn't mean that we are no longer required to do good works.