Recently I ventured into the world of the Internet. I carefully dipped my big toe in the waters of a bulletin board on Lordship Salvation. It has been very interesting. It was clear that the one writer, a seminary professor, understood this to mean that all genuine believers love Christ and that those who don't love Him are eternally condemned. That is not an isolated view.
Many commentators hold that opinion.
This verse is the only place in the entire NT where the idea of loving the Lord occurs using the verb phileo. However, very similar expressions do occur and they clearly show that loving the Lord Jesus is not the same as believing in Him. The Lord wouldn't have commanded them to keep His commandments and thereby love Him if all believers automatically obey and love Him. Loving Jesus Christ is not the same as believing in Him. The nature of the curse is not explicit in the word anathema.