The Christians of the New Testament recognised that there was one true image that represented God. In the first place this was humans - made in the image God. And then the true image of the invisible God appeared on earth. And returned to the Father.
And left on earth his body. It was the body of Christ that was the visible presence of God. The little gatherings scattered around the world were also the identity markers for the Christians. You knew who belonged to Christ because they met together with the others who belonged to Christ. That was the only marker you needed.
As it is now in many places, so it was then: belonging to the little gatherings was seen as a political and religious threat. Off and on throughout history the little gatherings have been closed down, or attacked, or threatened.
Unfortunately belonging to the body has ceased to be the chief symbol of a Christian and has been replaced with many others.
But the local gathering remains the true symbol of Christianity because it is the way the Father and the Son are present in his world through the Spirit. It is thus more than symbol. It is the community where God dwells with his people. It is the earthly version of heaven.
Dale