Assalam u alaikum. I am from Pakistan and now learning Islam, I also changed myself now to straight manhaj after being guided. But being an ignorant person, 3 years ago I wanted to talk to hindu person on social media and to seem harmless I showed myself as hindu guy but I swear to Allah, I never knew such an act is not allowed and is kufr and nobody even told me ever, it's just I learnt now when studying nullifiers of Islam. I merely took it as a lie at best and I believed that islam is from within heart and I'm just lying.Did I become a disbeliever by that? Will i have to retake shahada and redo nikah? Doing nikah again will create huge problem in family as they will think as I had divorced their daughter.

All perfect praise be to Allah, The Lord of the Worlds, and peace and blessing be upon the Messenger of Allah, his family, and all his companions.

As long as you did this while not knowing its ruling, then you have not committed Kufr (disbelief). Ibn Qudaamah said in Al-Mughni: "In the same way, whoever is ignorant of something is not judged to be a Kafir (non-Muslim) unless he is aware of it and he is cleared from doubt." [End of quote.]

Therefore, you do not have to renew your marriage contract, your marital bond remains valid, and your Islam is still intact, but you have to repent from lying.

Allah knows best.