It is better to focus on the Savior than it is to focus on salvation. It is easy to become so fearful about our spiritual standing that we take our eyes off the very One who is the answer to that fear.
Now it is true that the Scriptures tell us to both "examine ourselves to see if we are still in the faith" (2 Cor.13:5) and to "work out our salvation with fear and trembling"(Ph’p 2:12). However, one of the overarching themes of the Bible is the primary necessity of knowing Jesus in a visceral, experiential way. We are to love, seek and obey Him above all other things, one of those things being a constant sense of assurance about our eternal destiny.
Not every Christian will admit to having doubts about his or her salvation but most have had the experience at one time or another. The combination of our continuing moral imperfection and the accusations of our Adversary make it all too easy to worry about our standing with God. If every one of Christ’s followers automatically gained full and permanent emotional assurance of their salvation at the moment of conversion why would Paul , in 1st John, bother writing to believers about how they could know that they have eternal life?