This is a much debated subject Topaz, and there are a lot of good posts right here on the subject.
Okay, Jesus, what does He give? Eternal life? If you have eternal life and in, let's say ten years you lose it, it was a ten year life and whatever it was, it was not what Jesus gives. HE says "...and they shall never perish." Never is never. To say otherwise you are CORRECTING THE LORD. "Well now Lord, yes they CAN perish." We are totally incapable of ourselves to make it to heaven. We don't deserve to go there and we don't deserve to stay there. The only place we can get to by ourselves is hell.
Jesus alone gets us to heaven. Look at it this way: You book a ticket on an airline to go to Chicago, pay for your ticket, the ticket says your flight to Chicago departs a certain time and gate. You check in, go to that gate and get on that plane that they have announced was departing for Chicago. Now, where are they going to take you? Dallas? If we can trust the airline and those pilots to get us to where we should go, we can more than trust He who loved us and gave Himself for us. (Now, yes, planes do, tragically, crash: but not this flight, with this Pilot!)
Now we come to your supervisor. There is apparently no fruit in this persons life. It is by their fruits that ye shall know them. It is not that doing, or not doing things that get us to heaven, it is those things, works, that SHOW what has taken place within us.
If we are children, we are under the chastening and correction of our Heavenly Father. If one shows no sign that sin bothers him/her, they are not a child of God and not saved.