"Glory to God in the highest. And on earth peace, goodwill toward men!" Luke 2:14.
The Greek word "Irani" means "to join; wholeness, prosperity, union, oneness, completeness, health, wholeness, (shalom). Hebrews used "shalom" as a greeting coming and going - to bring opposites together. We have been brought together into oneness with God.
If you start to feel peace leaving you and your focus goes to your problem/stress/issues, just turn and look at Jesus - you are one with Him. When you look at Him, you are looking at yourself (the truth of who you really are).
What we celebrate at Christmas is the perfect gift to us. Peace. Oneness with God. Every promise, every prophecy, every good thing that we will ever need is given to us; is wrapped up in this one gift. He lived the perfect life for you. So you don't have to live the perfect life. You become one with Him and He lives through you.
In Jesus, God was reconciling all things unto Himself: men, women, Jew, Gentile, slave, free man, husband, wife. All become one in Jesus.