In his book Doubting, author Alister McGrath shared the following story to illustrate how we can know God loves us:

An aunt of mine died some time ago, having lived to be 80 or so. She had never married. During the course of clearing out her possessions, we came across a battered old photograph of a young man. My aunt had, it turned out, fallen hopelessly in love as a young girl. It had ended tragically. She never loved anyone else and kept a photograph of the man she had loved for the remainder of her life.

Why? Partly to remind herself that she had once been loved by someone. As she had grown old, she knew that she would have difficulty believing that, at one point in her life, she really had meant something to someone—that someone had once cared for her and regarded her as his everything. It could all have seemed a dream, an illusion, something she had invented in her old age to console her in her declining years—except that the photograph gave the lie to that.

It reminded her that it had not been invented; she really loved someone once and was loved in return. The photograph was her sole link to a world in which she had been valued.

The communion bread and wine are like that photograph. They reassure us that something that seems too good to be true—something that we might even be suspected of having invented—really did happen.