It's not as difficult of an answer as you might think.
What is unique about Christianity is the energy, effort, and movement to break the disconnect between God and humanity are all about God reaching out to us. We are only expected to do one thing.
We are not, in the Christian tradition, asked to practice rituals to connect with God. We are not asked to offer sacrifices, whether easy or painful. We are not asked to pray a certain number of times each day. We are not asked to detach ourselves from our surroundings, feelings. or experiences.
We are simply asked to believe.
Frankly, believing is more of a challenge than doing all of the things previously mentioned. Believing kills pride and the self satisfaction that whispers "I did it. I'm good enough. I'm following the rules. I'm OK all by myself because of what I've done."
What are we asked to believe?
We are asked to believe that God loves us so much and wants relationship with us so much that He became one of us, showed us how to live, paid our spiritual debts---also known as "redeemed us"--and now empowers us to live exactly as we were originally created, by Him, to live.
Certainly, Jesus Christ could have entered human experience mysteriously, without any clear physical origins and lived a distant, powerful human/divine life. People still would have been drawn to Him.
There are some very good reasons He chose not to do it that way.
When we are lonely, afraid, overwhelmed, in physical or emotional pain, we have a God who knows exactly what that feels like because He has been there, but transcended beyond those experiences and can lead us in that same process.
The incarnation means God chose to love us close up, not from a distance.
The incarnation means God sees sin as a horrible contagion from which we cannot cleanse ourselves, Study human history if you doubt this.
Having given us free will, God will not revoke it and change us into automatons of forced obedience. Instead, in redemption, He pays our bills, offers himself as a human/divine hybrid sacrificial substitute, and gives us a chance to live a life worth living.
This is a lot to believe, and yes, it's probably easier to follow rituals and practices than to wrap your brain around all of this and then make it the foundation for your life.
How do you do it?
You begin with this slightly modified version of an old prayer: "Lord, I want to believe. Help my unbelief."
This is really what Christmas is all about.
Perhaps you are surrounded by loving family or friends, or totally and utterly alone in the world. Perhaps you have made more money than ever this year, or you are broke and uncertain about next week's light or grocery bill. Perhaps you look forward to the new year because you expect it to the the best ever, or you dread the results of a negative medical report, living as an aging person while frail and alone, or you were just fired from a job you desperately needed.
Every emotion you have is known to Jesus Christ because He experienced all of them. He actually knows how you feel and welcomes you into a healing, loving relationship with Him.
That's the reason for the Incarnation.