How can someone know that he has passed out of death and into life? John 5:24 says, "Truly, truly, I say to you, he who hears My word, and believes Him who sent Me, has eternal life, and does not come into judgment, but has passed out of death into life." Many people today use such Scriptures as evidence of their salvation, because they know them to be true and put their trust in them. They know that eternal life can only be found in the Son of God, and they are not looking elsewhere. Yet even though they believe in the Scriptures, is their faith valid? Can they be deceived? After all, the Pharisees earnestly held to the Scriptures, but it didn't do them any good. Their belief was empty.
Fortunately, we can hear the gospels echoed in the epistles, which can help us to judge our true condition with greater clarity. What John heard the Master say, the words which he faithfully recorded, he also explained in his letters, the epistles. Thus we read in 1 John 3:14, "We know that we have passed out of death and into life, because we love the brethren. He who does not love abides in death." So from these two Scriptures just quoted, the Gospel of John and the epistle of 1 John, it becomes very clear -- he who believes has passed out of death and into life, and he who loves has passed out of death into life. So believe and love are synonymous, two words representing the same reality.
Unless, of course, you have a doctrine that makes you think that you can pass out of death and into life through a belief that does not produce a life of loving your brothers. In that case, you have a different opinion from the apostle John. He could see the time coming when there would be such a great falling away from true faith, the faith that he was so familiar with. This great falling away is called apostasy, when men would say that they loved the Master but would not love His words or love the brethren. So he defined love in case there was any doubt: "We know love by this, that He laid down His life for us; and we ought to [must] lay down our lives for the brethren."1
After all, it was this man, John, who heard right from the mouth of the only begotten Son of God, "A new commandment I give to you, that you love one another, even as I have loved you, that you also love one another."2 But just to make sure, in his epistle, John spelled out in no uncertain terms what it meant to love in the same way as our Master loved:
But whoever has the world's goods, and beholds his brother in need and closes his heart against him, how does the love of God abide in him? Little children, let us not love with word or with tongue, but in deed and truth. We shall know by this that we are of the truth, and shall assure our heart before Him. (1 John 3:17-19)
So how do we assure our heart before Him? By loving Him? "The one who does not love his brother whom he has seen, cannot love God whom he has not seen."3 Only disciples love as He loved, because they have forsaken everything in order to become like Him. "The one who says 'I have come to know Him,' and does not keep His commandments, is a liar, and the truth is not in him."4 If we think we are loving God when we are not living to benefit our brother, we are not loving with the love that John knew was proof we had passed out of death and into life. John knew that a mystical love, the kind without practical expression, was the work of a deluding spirit.