A favorite question of non-Catholics is: do you know you are saved? Most Catholics will answer no, I don’t know with 100% assurance that I’m saved. The non-Catholic then shows how unbiblical this Catholic belief is by reciting 1 John 5:13: “I write these things to you so that you may know that you have eternal life.” The emphasis is on “knowing”, not guessing or hoping, but knowing that we have eternal life. This is known as “assurance of salvation” and most non-Catholics believe that once a person is “saved” they cannot be “unsaved”. No sin can separate them from God.
A Catholic should, at this point, ask what things has John written to tell us we have eternal life? Does John say a person must accept Jesus as their personal lord and savior to know they have eternal life? Yes, but that’s only part of it.
Chapters 1-4 of 1 John are full of statements that start “If you…” and “Whoever…”. For example, “If we say, ‘We have fellowship with him,’ while we continue to walk in darkness, we lie and do not act in truth. But if we walk in the light as he is in the light, then we have fellowship with one another, and the blood of his Son Jesus cleanses us from all sin.” (1 Jn 1:6-7) and “Whoever says he is in the light, yet hates his brother, is still in the darkness.” (1 Jn 2:9). Check it out for yourself; there are a lot of these statements.
What do they all mean? Well, these are the things John has written to us that we may “know we have eternal life”. Must I accept Jesus as my personal lord and savior as Protestants say? Yes! However, you can’t stop there, you need to walk in light, you need to love your brother and on and on.
How does this jive with the rest of the Bible? Paul says in Phil 2:12 to “work out salvation with fear and trembling”. He also says “…for fear that, after having preached to others, I myself should be disqualified.” (1 Cor 9:27). Jesus tells us to “work” for the bread of life in John 6:27.
A Catholic CAN know he has eternal life; by tapping into the grace of Jesus through the power of Confession we can be cleansed of our sins so we have fulfilled all the “ifs”. However, if we don’t follow one of those ifs (sin) we no longer have that guarantee of eternal life and need to get back on track!