It's not a different standard, it's a new door into grace so that people can get help with overcoming their sin. The standard of good conduct is still preached in the rest of the New Testament.
Being judged by our conduct and being eternally saved by not being wicked was not altered at the cross but continued to be affirmed in the New Testament as can be seen by:
Peter, who told someone he just needed to repent and made no mention of Christ: "You have neither part nor lot in this matter, for your heart is not right in the sight of God. Repent therefore of this your wickedness, and pray to God, if perhaps the thought of your heart may be forgiven." (Acts 8:21-22)
Peter also said, "I now realize how true it is that God does not show favoritism but accepts men from every nation who fear him and do what is right.” (Acts 10:34-35)
James said works are necessary because faith by itself is useless: “Faith, if it has not works, is dead, being alone.” (2:17)
John records what he saw in a vision: “I saw the dead, great and small, standing before the throne, and books were opened. Another book was opened, which is the book of life. The dead were judged according to what they had done as recorded in the books. The sea gave up the dead that were in it, and death and Hades gave up the dead that were in them, and each person was judged according to what he had done.” (Rev. 20:12)
John also said, “The world and its desires pass away, but the man who does the will of God lives forever.” (1 Jn. 1:17)
And then, as if to clarify what John wrote about what Jesus said regarding being born again in the third chapter of John, he says, “Everyone who does what is right has been born of him (God). (1 Jn. 2:29)
Paul informs us the wrath of God is brought on by poor conduct, not lack of faith: “The wrath of God is being revealed from heaven against all the godlessness and wickedness of men who suppress the truth by their wickedness.” (Rom. 1:18)
Paul taught you must prove your repentance by your deeds, not prove your faith by your works: "To the Gentiles also, I preached that they should repent and turn to God and prove their repentance by their deeds." (Acts 26:20)
Paul, writing to Christians, explains how Christians will receive eternal life: “For [God] will render to every man according to his works: to those who by patience in well-doing seek for glory and honor and immortality, he will give eternal life...” (Rom. 2:6-7)
Paul taught us that the heathen who never performed the outward acts of the Jewish Law such as circumcision or keeping the Sabbath would be counted as if they had if they fulfilled the righteous requirements of the Law: “If those who are not circumcised keep the law's requirements, will they not be regarded as though they were circumcised?” (Rom. 2:26)
Then Paul adds this doosey: "Work out your own salvation with fear and trembling." (Php. 2:12) What? What’s there to work out and be afraid of when you have faith? Did Paul not get the memo that there is nothing to work out for those who have faith?
The writer of Hebrews said their salvation depends on their work and labor of love, not their faith: “But that which bears thorns and briers (evil works) is rejected, and is nigh unto cursing; whose end is to be burned. But, beloved, we are persuaded better things of you, and things that accompany salvation, though we thus speak. For God is not unrighteous to forget your work and labor of love, which you have shewn toward his name, in that you have ministered to the saints, and do minister.” (Heb. 6:8-10)
And finally, the words of Jesus. Have you seen the tract called The Romans Road to Salvation? Here’s the Matthew Road to Salvation:
Many will say to me in that day, “Lord, Lord, have we not prophesied in your name? And in your name have cast out devils? And in your name done many wonderful works?” And then will I profess unto them, “I never knew you: depart from me, you that work iniquity.” (Mt. 7:22-23)
The good man brings good things out of the good stored up in him, and the evil man brings evil things out of the evil stored up in him. But I tell you that men will have to give account on the day of judgment for every careless word they have spoken. For by your words you will be acquitted, and by your words you will be condemned. (**Mt. *12:35-37)
He answered, "The one who sowed the good seed is the Son of Man. The field is the world, and the good seed stands for the sons of the kingdom. The weeds are the sons of the evil one, and the enemy who sows them is the devil. The harvest is the end of the age, and the harvesters are angels. "As the weeds are pulled up and burned in the fire, so it will be at the end of the age. The Son of Man will send out his angels, and they will weed out of his kingdom everything that causes sin and all who do evil. They will throw them into the fiery furnace, where there will be weeping and gnashing of teeth. Then the righteous will shine like the sun in the kingdom of their Father. He who has ears, let him hear. (Mt. 13:37-43)
For the Son of Man is going to come with his angels in the glory of his Father, and then he will repay each person according to what he has done. (Mt. 16:27)
Then he will say to those on his left, “Depart from me, you who are cursed, into the eternal fire prepared for the devil and his angels. For I was hungry and you gave me nothing to eat, I was thirsty and you gave me nothing to drink, I was a stranger and you did not invite me in, I needed clothes and you did not clothe me, I was sick and in prison and you did not look after me.” They also will answer, “Lord, when did we see you hungry or thirsty or a stranger or needing clothes or sick or in prison, and did not help you?” He will reply, “I tell you the truth, whatever you did not do for one of the least of these, you did not do for me.” Then they will go away to eternal punishment, but the righteous to eternal life. (Mt. 25:41-46)
That’s five times the writer of Matthew quotes Jesus in a way that does damage to the doctrine of salvation by grace. It’s almost as if someone purposefully put all this at the beginning of our New Testaments so we wouldn’t miss the fact God did not overturn his Old Covenant standard of salvation by not doing evil.
And yet, Evangelicals miss that fact.
Not to be outdone by Matthew, the apostle John also quotes Jesus saying the same things:
Do not marvel at this, for an hour is coming when all who are in the tombs will hear his voice and come out, those who have done good to the resurrection of life, and those who have done evil to the resurrection of judgment. (Jn. 5:28-29)
Look, I (Jesus) am coming soon, bringing my reward with me to repay all people according to their deeds. (Rev. 22:12)
When Jesus comes back (or came back if you're a Preterist) he's going to be looking for orthopraxy (right living), not orthodoxy (right belief). No one will be judged by what he believes. Everyone will be judged by what he has done. Those who do wicked deeds need to turn from those deeds before it’s too late. It’s as simple as that.
