On the evening of Resurrection Day

On the evening of Resurrection Day:

"...when the disciples were together, with the doors locked for fear of the Jewish leaders, Jesus came and stood among them and said, 'Peace be with you!' After he said this, he showed them his hands and side. The disciples were overjoyed when they saw the Lord."

(John 20:19-20). 

Fifty days later, 

"he was taken up before their very eyes, and a cloud hid him from their sight" (Acts

1:9). 

Shortly thereafter was the Day of Pentecost, 

the day the true church began, not a building, but a body of believers in the death and resurrection of Jesus Christ. 

That's why Resurrection Day, including Jesus' birthday, is intimately special to true believers.

Blessings!