False. Long before Constantine, the apostle Paul wrote extensively (and in depth) that Christian and Jewish ideas needed to be separated.
The Jews of Christ's day had come to the false conclusion that they could establish their own righteousness by becoming Torah observant (and more than Torah observant as seen in the teachings of the Pharisees). However, they were tithing mint, cumin, and herbs, but forgetting the weightier matters of the Law. So Christ exposed them as hypocrites, and warned His disciples about the leaven of the Pharisees.
Paul himself was a Pharisee of the Pharisees. He could have claimed to be the most Torah observant Pharisee. But the Lord Jesus Christ opened his eyes to the truth, brought him to repentance, and showed him that no man can be justified by Torah observance (keeping the Law). For the simple reason that they were breaking the Ten Commandments while they were supposedly observing all the other commandments.
Then Paul went on to show us (by divine inspiration) that (1) there is none righteous, no not one, and (2) that only those who are justified by grace through faith (as was Abraham) are saved by grace and become children of God.
But many Pharisees were also saved during that time, and refused to accept the fact that the Old Covenant had been replaced by the New Covenant, and the Law of Moses had been replaced by the Law of Christ. So some of then started teaching Christians that unless they were also circumcised and became Torah observant, they were not really saved. So Paul had to address these Judaizers in the epistle to the Galatians.
Then God led him to write the epistle to the Hebrews to show Jewish Christians that the Law of Moses had been FULFILLED by Christ, and that everything pertaining to the temple, the Levitical priesthood, the animal sacrifices, the feasts, festivals, sabbath days, and all ceremonial observances were finished. But the Ten Commandments remained within the New Covenant, and were now written on hearts and minds, not on tablets of stone.
Now if anyone tries to revive Torah observance, they are DEFYING God and Christ, not Paul or any apostle. God made it clear in Acts 15 that there were four things which carried over from the Torah, and in fact some of them were from the time of Noah.
For it seemed good to the Holy Ghost, and to us, to lay upon you no greater burden than these necessary things; That [1] ye abstain from meats offered to idols, and [2] from blood, and [3] from things strangled, and [4] from fornication: from which if ye keep yourselves, ye shall do well. Fare ye well. (Acts 15:28,29)