The notion that sexual union is the closest thing to experiencing the divine or a spiritual connection is often associated with certain spiritual traditions, philosophies, and mystical teachings. It is important to note that views on this topic can vary across different cultures, religions, and belief systems.

1. Symbolism of Unity and Creation:
   Sexual union is often seen as a symbol of unity and creation. It represents the joining of two individuals, both physically and emotionally, in a deeply intimate act. This union has the potential to create new life, which is considered a profound and awe-inspiring process. The ability to participate in the creation of life is often seen as a divine or sacred aspect of human existence.
2. Spiritual and Energetic Connection:
   Some belief systems emphasize the idea that sexual energy is a powerful force that can connect individuals not only on a physical level but also on a spiritual and energetic level. It is believed that during sexual union, there is a merging of energies, a blending of masculine and feminine polarities, which can lead to a heightened sense of oneness and transcendence. This sense of unity can be seen as a reflection of the divine unity often sought after in spiritual practices.
3. Mystical Traditions and Tantra:
   In certain mystical traditions and practices, such as Tantra, sexual union is considered a sacred and spiritual experience. Tantra embraces the idea that sexual energy can be harnessed and used for spiritual growth, self-realization, and achieving a deeper connection with the divine. It involves practices that focus on mindful and intentional sexual experiences, seeking to transform ordinary physical union into a profound spiritual encounter.
4. Metaphorical Expression of Divine Love:
   For some, the belief that sexual union is a metaphorical expression of divine love and the ultimate experience of connection stems from a recognition that love, in its purest form, can transcend boundaries and bring individuals closer to a sense of spiritual transcendence. It is the deep connection and profound intimacy experienced in sexual union that is seen as a reflection of the divine love that permeates the universe.

It is important to approach these beliefs with cultural sensitivity and to recognize that views on sexuality and spirituality can vary greatly. While some may find spiritual significance and meaning in sexual union, it is not a universally held belief, and other perspectives on the divine and spiritual connection exist.

Ultimately, the interpretation of sexual union as a connection to the divine is a deeply personal and subjective matter, rooted in individual beliefs, cultural contexts, and spiritual practices.