What makes a day holy?
God said it's holy.
Well, that's easy enough. But why does He (or did He) declare certain days to be holy?
He sanctified Saturdays by resting on the first Saturday and declaring it to be hallowed and set aside for rest for us. He made it holy for our benefit, and to test and demonstrate our faith in Him. That is, to see if we would trust in Him to sustain us.
He sanctified Sundays by rising from the dead on the first day of the week. He set it aside as a day for us to assemble and worship and fellowship and pray and serve and learn from His Word.
He sanctified the feasts days in the Old Testament by commandment and each for specific purposes.
He re-sanctified two of the feast days specifically (Passover & Pentecost) in the New Testament through His death (as the Passover Lamb) and by baptizing His people with the Holy Spirit (on Pentecost).
He hallowed a day (practically, though not by revelation or commandment) by being born. And, though we do not necessarily celebrate the birthday of the Son of God on the correct date on our calendar, yet we do celebrate (and rightly so) the entrance of the divine into our earthly experience by celebrating Christmas. In America we have many holidays. It takes no genius to see that even our minor celebrations (Columbus Day or Father's Day, etc.) are simply ways that we mimic the example set by God Himself; the practice of setting aside specific times to remember certain events or people or truths or whatever, and to honor that which should be honored. In this way, we hallow things ourselves. These are holidays - holy days to us.
We should consider soberly what it is that we are hallowing. Are we honoring the right things? Are we honoring minor things more than major things? Are we guilty of replacing things of eternal significance with things of mere earthly value?
Today is a holiday in my house. It's my wife's birthday. Today she is 46 years young. I believe it is holy and good for me to hallow this day. God created her a beautiful and wonderful woman. She is the love of my life and the joy of my every day. She is God's gift to me. Today I celebrate her! I celebrate the fact that she was born on this day 46 years ago. I hope and pray that God gives her 46 more years and the I get to be around to celebrate every one of those birthdays too. Today is a holy day for us. We set today aside from all other days. It's her day. Today I want to render joyous honor to my most favorite person on earth; my wife, Tonya.
Happy birthday sweetheart!