The Jews expected a victorious Messiah, accompanying His conquests by signs, and the establishment of the kingdom of Israel. In the mind of a Jew the claim that Jesus was the Christ was utterly refuted by the Cross. To Gentiles such a testimony was an impossible standard of wisdom. Celsus, who wrote against Christianity in the second century, speaks of Christians as “actually worshiping a dead man,” regarding this as a proof of the absurdity of the Christian faith. — Vine, page 13.
we (v.23) — emphasized
The subject of Gospel preaching is a Person — CHRIST. Christianity is not a theory about Christ; it is not a series of ethical statements proceeding from Christ; it is not a system built upon the concepts OF Christ. Christianity IS Christ! Christianity is not a cold, dead organization; it is a living organism, and it could not survive if Christ were removed from it, because He is the head and foundation of it. — Greene, page. 73.
stumbling block (v.23) — from Greek word for “a trap” — hindrance
those who are called (v.24) = “to the called themselves” — the same people referred to as “us” in v. 18 — The called know they are called in their own experience.
This simply means that whether Jew or Greek, those who hear the Gospel, who believe the Gospel, are saved — and that they KNOW what happens in their own hearts. — Greene, page 77.
foolishness/weakness of God (v.25) — from the viewpoint of man