How is Christ both a stumbling stone and a cornerstone?

In Romans 9:33, Paul highlights that Christ serves dual roles: as a stumbling stone for those trying to achieve righteousness through their works, and as a cornerstone for those who believe in Him. This paradox illustrates how Christ is perceived differently based on one's approach to salvation. For those relying on their merit, the idea that salvation is solely through Christ's grace presents an offense—revealing their inability to meet God's standards. In contrast, for true believers who rest in His righteousness, Christ is the cornerstone that supports their faith and guarantees their salvation, symbolizing hope, security, and safety.