Salam dear brother!How can we marry from among the People of the Book whereas in sura 9.29 we are told to fight them?

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.

All these rulings are from Allah Almighty; the One Who made it permissible for us to marry women from the People of the Book, is the One Who commanded us to fight them, so there is no contradiction in His Revelation.

Allah Says (what means): {Then do they not reflect upon the Qur'an? If it had been from [any] other than Allah, they would have found within it much contradiction.} [Quran 4:82]

If one thinks that there is a contradiction, then we have to admit that it is due to the deficiency in our minds.

Besides, the permission to fight them does not contradict the impressibility of marrying their women. Allah has even commanded us to fight the oppressive group of Muslims; Allah Says (what means): {…But if one of them oppresses the other, then fight against the one that oppresses….} [Quran 49:9]

But Allah did not forbid marriage with the women of this oppressive group. It is known that a woman is not killed in war as it is forbidden in Islam to do that, unless she participates in the fighting.

Moreover, the People of the Book are not fought against in all cases; they are only fought when they fight against the Muslims, but if they are peaceful with Muslims, then there is no war or fighting with them.

Allah Says (what means): {… Allah does not forbid you from those who do not fight you because of religion and do not expel you from your homes - from being righteous toward them and acting justly toward them. Indeed, Allah loves those who act justly. Allah only forbids you from those who fight you because of religion and expel you from your homes and aid in your expulsion - [forbids] that you make allies of them. And whoever makes allies of them, then it is those who are the wrongdoers.} [Quran 60:8-9]

The same thing applies when they agree to pay the Jizyah to the Muslims, then they are not fought against as in the verse which you referred to in the question in Surah at-Tawbah (The Repentance).

For more benefit on Jizyah, please refer to Fataawa ">200541 and 59982.

Allah knows best.