The birth of Jesus made it possible for people to see, hear, touch, and hold Jesus (see 1 Jn 1:1ff). It made it possible to have a personal relationship with Him.
Jesus' Ascension, the giving of the Holy Spirit at Pentecost, and the birth of the Church made it possible for all people to have a much more personal, deep, and intimate relationship with Jesus (see Catechism, 788). Astoundingly, we can even live inside Jesus while He lives inside us (see Jn 14:20; 17:23). We can even receive into our bodies the body and blood, soul and divinity of Jesus. This double indwelling is a relationship beyond all human experience of intimacy. It is a miracle and a mystery of abiding in the One Who is Love Himself (1 Jn 4:16). We are "able to grasp fully, with all the holy ones, the breadth and length and height and depth of Christ's love, and experience this love which surpasses all knowledge, so that (we) may attain to the fullness of God Himself" (Eph 3:18-19). Our entry into and abiding in the mystery of divine love is done by the Holy Spirit, especially working through the Church, in Baptism and the Eucharist.
Christmas is prime time for receiving divine love, for Christmas takes us back to the roots of God's incarnate love. Have a Christmas in the mystery of holy love.