In fact ; it was fro, the beginning before GOD create human beings
and GOD knows that he will sacrifice for human being throug the cross .the cross has many wonderful and great meanings :
1- it is the sign of connection between earth and heaven
2- it also represents the all human being from right and left
3- the cross means that GOD take us from death to eternal life and from left " weakness" to right " power "
4- the cross is only way that GOD is opening his arms to all the people and saying come to forgiveness i will die for your sins , come in and let me take your sins in the cross and die instead of you
5- the cross represent the great power of God as he save all the humanity by the same method devil deceived man , Satan made Adam eat from a tree so Adam had the punishment of eternal death , and jesus on the cross resembles a good seeing and eatable apple on the tree
so as man punished fro eating from the tree by the deceiving of devil also god save hauman by a cross from the tree
6- there was many symbols in the old testament resemble the cross we will talk about later
thanks