Well here is the selection of English translations of 1 Corinthians 1-18 from
Bible Gateway, four of which are below:
For the message about the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. NRSV(A).
For the message of the cross is foolishness to those who are perishing, but to us who are being saved it is the power of God. NIV
For the preaching of the cross is to them that perish foolishness; but unto us which are saved it is the power of God. KJV
For the message of the cross is foolishness [absurd and illogical] to those who are perishing and spiritually dead [because they reject it], but to us who are being saved [by God’s grace] it is [the manifestation of] the power of God. AMP
Now our preacher on Sunday was talking about why we go to church, after we have believed and been baptised, and he said it is not supposed to be just to see our friends, get a free cup of coffee, because we have always gone or our parents told us to go. It is to build our relationship with Jesus and to learn the Bible, constantly. We hear a Psalm, a short piece of the Old Testament, and a short piece of the New Testament every week. We also hear a lesson about the New Testament verses which we heard, and there is a Eucharist. We make a joint admission of our sins, and pray together.
Now that I am simply managing to look at the entire verse it seems to make sense to me, everything we do in church is about the message of the Cross having the power of God, and that is why we go. To those who reject and do not accept the power of God in the message of the Cross, we are just a bunch of fools who are wasting our time. The preacher was saying also to tell people who do think we are fools who waste our Sunday mornings, that if they accept being saved, they can come and witness the power of God for themselves. He is trying to get more people to come to church, it is part of his job description.
btw I put the text in purple for the versions of the Bible he was allowed to be teaching from, and now, despite the fact I have ceased to be puzzled, (just by reading the whole verse

- at myself), I am interested in why the oldest translation that he could have used says "saved" and all the more modern translation have "being saved".