Afterward came also the other virgins, saying, Lord, Lord, open to us. But he answered and said, Verily I say unto you, I know you not. Matt. 25:11, 12.
There is a big difference between "only believe" and the genuine faith relationship with God. The nominal Christian world has for years held unto "only believe" as its brand of faith. But intellectual assent has never been sufficient for salvation. The person who has a vital relationship with God from which genuine faith springs, is the only one who can really accept of Christ's sacrifice on a continuing basis.
Insofar as our reception of eternal life is concerned, the relationship of knowing God, of loving Him, of trusting in Him, is the entire basis of the Christian life. Eternal life is based upon Jesus and what He has done, but there is a part we have to play. We must accept and receive it, or we never benefit from it personally.
When we first accept of His grace, at justification, the relationship with Christ begins. As we continue to accept of His grace on a daily basis, the relationship continues. It's like a marriage. Which is more important, getting married, or staying married? In the end you'll have to admit that this is a nonsensical question! You can't stay married if you have never gotten married in the first place, and getting married is worth nothing unless you stay married. They are both important; they are both necessary. Both as equally vital.
Jesus told about a wedding party in Matthew 25. When it got down to the nitty-gritty, and the five foolish virgins were asking admission to the wedding, the Lord answered them, I know you not. It's said again in Matthew 7:23, "Then will I profess unto them, I never knew you: depart from me, ye that work iniquity." The ones to whom these words were addressed had done a lot of working. They had said, Lord, Lord. They knew how to mouth the name of Jesus. They had cast out devils and been involved in many wonderful works. But they didn't know Him. Those who are lost someday will be those who don't know Him. Do you know Him today? Have you accepted again today of His sacrifice? Have you spent time in communion with Him?