God calls those he chooses to Jesus. If they decide to believe and follow Jesus, they will have their sins washed away and gain eternal life. Christians are saved by the grace of God. The Gospel of the Kingdom of God that Jesus proclaimed helps some Christians understand God’s grace. Many today, like those in the first century, are still mired in legalism. In the first century, the first converts came out of Judaism. Being reared as Jews, some felt the Mosaic laws and customs should apply to Christians. They were particularly concerned with who could become a Christian. They believed only those who were circumcised could be saved and would not have fellowship with those who were uncircumcised. Paul was called to evangelise to the gentiles and vigorously opposed those early Christian’s traditional Jewish beliefs. Paul knew God would call those he wanted and God’s grace was for those with a pure heart.

Galatians 5:11-13 Amplified Bible
11 But as for me, brothers, if I am still preaching circumcision [as I had done before I met Christ; and as some accuse me of doing now, as necessary for salvation], why am I still being persecuted [by Jews]? In that case the stumbling block of the cross [to unbelieving Jews] has been abolished. 12 I wish that those who are troubling you [by teaching that circumcision is necessary for salvation] would even [go all the way and] castrate themselves! 13 For you, my brothers, were called to freedom; only do not let your freedom become an opportunity for the sinful nature (worldliness, selfishness), but through love serve and seek the best for one another.

1 Corinthians 7:18 King James Version
18 Is any man called being circumcised? let him not become uncircumcised. Is any called in uncircumcision? let him not be circumcised.
Romans 2:25-29 Modern English Version
25 Circumcision indeed has merit, if you keep the law, but if you are a breaker of the law, your circumcision becomes uncircumcision. 26 Therefore, if an uncircumcised man keeps the righteousness of the law, will not his uncircumcision be counted as circumcision? 27 Will the uncircumcised one who is righteous by nature, if he fulfills the law, not judge you who, by the letter of the law and circumcision, violate the law? 28 He is not a Jew who is one outwardly, nor is circumcision that which is external in the flesh. 29 But he is a Jew who is one inwardly. And circumcision is of the heart, by the Spirit, and not by the letter. His praise is not from men, but from God.

What are the legalistic laws that Christians still follow? Do you need to keep them?