Greentext

The core of Christianity is originally the redemption, not the threat that necessitates it and often is more prominent.

The cross is a symbol of the sacrifice made to redeem people from the threat of hell. More relevant here is that sin separates humans from God, and through that sacrifice, the connection is restored. It is a catalyst of redemption and reunion. In that sense, they don't so much pray towards an implement of torture as an implement of liberation, salvation and mercy.

Given that those are hard things to put in a visual, tangible form and that humans tend to place a lot of value in visual, tangible representations, it's basically the simplest symbol you could come up with as a nascent cult.

It's not the only symbol, and particularly during the rise of the Roman church, you'll note that icons of saints become very common too. Some places will even have the Crucifix feature the crucified Jesus as well, to drive home the point about sacrifice and gratitude.

Protestants later held that the worship of saints was tantamount to idolatry and did away with them again, leaving just the core of the message of redemption. There was in some places a conscious choice to pick the "empty" cross rather than the crucified saviour as a symbol that he is no longer dead.

All in all, given his divine wisdom and love for metaphors and similes, I'd think Jesus would understand the point of the cross...

...then proceed to trash the place out of rage over the waste of money and effort that went into gaudy churches and gold-embroidered robes instead of helping the sick and poor.