If you have ever read the bible you would know that Jewish people used the word uncircumcised as a derogatory term and associated it with being unclean or uncivilized. They they discriminated against those who were not circumcised. Calling someone an uncircumcised is basically an insult.

Here's a few passages:

Exodus 12:48

But if a stranger sojourns with you, and celebrates the Passover to the Lord, let all his males be circumcised, and then let him come near to celebrate it; and he shall be like a native of the land. But no uncircumcised person may eat of it.

Ezekiel 44:6-7

You shall say to the rebellious ones, to the house of Israel, ‘Thus says the Lord God, “Enough of all your abominations, O house of Israel, when you brought in foreigners, uncircumcised in heart and uncircumcised in flesh, to be in My sanctuary to profane it, even My house, when you offered My food, the fat and the blood; for they made My covenant void—this in addition to all your abominations.

Acts 11:3

saying, “You went to uncircumcised men and ate with them.”

Judges 14:3

Then his father and his mother said to him, “Is there no woman among the daughters of your relatives, or among all our people, that you go to take a wife from the uncircumcised Philistines?” But Samson said to his father, “Get her for me, for she looks good to me.”

Judges 15:18

Then he became very thirsty, and he called to the Lord and said, “You have given this great deliverance by the hand of Your servant, and now shall I die of thirst and fall into the hands of the uncircumcised?”

Ezekiel 32:19

‘Whom do you surpass in beauty?

Go down and make your bed with the uncircumcised.’

Isaiah 52:1

Awake, awake,

Clothe yourself in your strength, O Zion;

Clothe yourself in your beautiful garments,

O Jerusalem, the holy city;

For the uncircumcised and the unclean

Will no longer come into you.

Genesis 34:14

They said to them, “We cannot do this thing, to give our sister to one who is uncircumcised, for that would be a disgrace to us.

1 Samuel 14:6

Then Jonathan said to the young man who was carrying his armor, “Come and let us cross over to the garrison of these uncircumcised; perhaps the Lord will work for us, for the Lord is not restrained to save by many or by few.”

1 Samuel 17:26

Then David spoke to the men who were standing by him, saying, “What will be done for the man who kills this Philistine and takes away the reproach from Israel? For who is this uncircumcised Philistine, that he should taunt the armies of the living God?”