and you have reference for this?
Actually, specifically, no. I used to have a reference that explained that the Romans started out with a simple one piece pole and it became more sophisticated from that to various shapes, like the X, T, then t. But I can't find it. What I do have is this:
The Imperial Bible-Dictionary says that the word
staurosʹ “properly signified a
stake, an upright pole, or piece of paling, on which anything might be hung, or which might be used in impaling a piece of ground. . . .Even amongst the Romans the
crux (Latin, from which our
cross is derived) appears to have been originally an upright pole.”
The Catholic Encyclopedia states: “Certain it is, at any rate, that the cross originally consisted of a simple vertical pole, sharpened at its upper end.”
There's a lot of confusion on several levels. First, the Greek word stauros and the Latin crux can mean a simple stake or, later various other shapes. Second, the term crucifixion is often thought to mean hung on a cross, when actually it meant attached to something, like a tree, a pole, a cross, or even, like Prometheus, the ground or rocks.
Also, the symbol of the cross was used long before Romans and Christ came along. But not necessarily used as an implement of death. You have to ask yourself, why would a troop of Roman soldiers, usually traveling in rocky terrain where trees were sparse, use two pieces of lumber to execute usually more than one person when a single piece or tree would suffice?
In the case of Jesus' death, whom the Jews obviously had some control over, which is indicated by their habit of breaking the legs of the victim so as to avoid a Sabbath, would obviously object to a phallic symbol as a means of punishment.
But ultimately it is Peter and Paul's use of the Greek word xylon in application to Jesus' death because this word, unlike stauros and crux, can only be used for a single piece upright pole as was the Jewish custom.