As salami alaikum. I live in a non-Muslim country. In the month of ramadan, I was fasting and I was passing by sone wonen in front if a library displaying sone books. They said to me, "Do you want to take a book to see what the future holds"? When I looked at the books I saw that they were books about Bible. So I didn't want to take them and to leave the place. I replied to them, without much thought, "May be sometime later, I am in a bit of hurry". So they let me leave. But I am feeling guilty and worried that I should have made it clear to them that I am a Muslim and don't want to read their christian books. Allah forbid, is what I said considered as Kufr? I did nit intend to read it later I just wanted to leave them as early as possible. Please tell me whether I committed sin by this and also tell me how to repent and what should be the correct response to such preachers?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

You are not sinful for saying this sentence, let alone having committed Kufr because of it. You do not have to explain to them that you are a Muslim.

You have done well by not taking those books and do not take them again, as it is impermissible to read books of misguided people except for a correct purpose, like a scholar who reads them in order to refute the falsehood in them and so on.

Jaabir narrated that ‘Umar came to the Prophet and said: “We hear narrations from the Jews, which we like, should we write some of them? He (the Prophet) said: "Are you in doubt, as were the Jews and the Christians? I have brought it (Islam) to you pure and white [i.e. free from any fault], and were Moses alive he would have followed me (without having any other alternative)." [Ahmad, and Al-Albaani classified it as Hasan]

There is no particular method to respond to those preachers; it is enough to turn away from them.

Allah knows best.