Romans 9:30 What shall we say, then? That Gentiles who did not pursue righteousness have attained it, that is, a righteousness that is by faith; but that Israel who pursued a law that would lead to righteousness did not succeed in reaching that law. Why? Because they did not pursue it by faith, but as if it were based on works. They have stumbled over the stumbling stone, as it is written, “Behold, I am laying in Zion a stone of stumbling, and a rock of offense; and whoever believes in him will not be put to shame.”
1 Corinthians 1:23 but we preach Christ crucified, a stumbling block to Jews and folly to Gentiles,
John 6:27-29 Do not work for the food that perishes, but for the food that endures to eternal life, which the Son of Man will give to you. For on him God the Father has set his seal.” Then they said to him, “What must we do, to be doing the works of God?” Jesus answered them, “This is the work of God, that you believe in him whom he has sent.”
Acts 16:30-34 Then he brought them out and said, “Sirs, what must I do to be saved?” And they said, “Believe in the Lord Jesus, and you will be saved, you and your household.”
1 John 5:12 Whoever has the Son has life; whoever does not have the Son of God does not have life.
By all appearances, the Gentiles found righteousness even though it did not seem that they really looked for it. By all appearances, Israel seemed to work for the righteousness of God with everything it had, but did not find it. What was the difference? Why did the unlikely Gentiles find righteousness, when the likely Jews did not? Because the Gentiles pursued the righteousness of faith, and the Jews pursued the law of righteousness. The Gentiles who were saved came to God through faith, receiving His righteousness. The Jews who seem to be cast off from God tried to justify themselves before God by performing works according to the law of righteousness. (Guzik)
There appears to be this huge stone that trips many multitudes of people up. Rather than trust in, rely on, and cling to Jesus Christ alone they choose to either flat out deny one true God exists and this is His plan and purpose for mankind, neglect, and complacency toward things of God and thereby can not recognize the difference between the worldly and things of God, or they, like many try to be right before God by performance (doing things that seem right in their own eyes as a means to be acceptable before God). All of these will lead people straight to hell for eternity. Don’t get me wrong about good works. We are to do good works, but not so that we are right before God, but rather to bring honor and glory to Jesus Christ.
Surrender of self-reliance, self-worth, and self-independence to belief, faith, trust, reliance, and obedience in, too, and on Jesus Christ alone is God’s plan and purpose for all of mankind. His Word says we should know Him by the mere fact of creation, but what has man done? They say creation was from a big bang that happened before time and from the existence of nothing. His Word says we should believe and trust in His Son, Jesus Christ, but many have deemed this to be nothing more than a fairy tale. His Word says the only way to be right in God’s eyes is to believe in, cling to, trust in, and rely on Jesus Christ alone, but many have turned this into works of themselves so that by doing them God is, by some means, required or obligated to give us eternal life. Nothing could be further from the truth. Salvation through Jesus Christ is a gift from God. Other than believing faith, trust, and reliance in Jesus Christ will anyone receive this gift from God.
