One represents the relationship between God and man. The first half is to pray for God (about 15: 7), and the second half is to read the Bible, listen to God's words, and teach people to repent and confess their sins (about 8: 3 1-32).
One horizontal is the relationship between people, and people love each other.
Whether vertical or horizontal, everything is meaningful, because Christ is the mediator (about15: 5; About 1 2:)
If we don't rely on Christ, God and people, people can't be connected together, just like facing each other across a river without a bridge.
Without Christ, God will not listen to the prayers of sinners, and people will not listen to God, so that person will only go to eternity. Today, the reason why God can listen to people's prayers and answer people's entreaties is precisely because of the Lord as the mediator.
Without Christ, there is no love in people's hearts, and people will argue, hate and fight with each other ... even if God does not destroy people, people will destroy themselves.
To sum up, the meaning of the cross can be:
Savior of life
Two relationships (God and man, man and man)
Three actions (self-denial-taking up the cross-following the Lord)
The four powers that Christ acquired (prayer, word of God, fellowship, witness)
Five waiters