Repentance from Spreading Anti-Islamic Materials
Question

I was a misguided person spreading secularist ideologies, and writing heretical stories and articles, and using my poetry as a vehicle to spread corruption and liberalism. Then Allah turned to me with His mercy and brought me forth from darkness into light. How should I repent?
Praise be to Allah.This of course is a great blessing of Allah and a favor. We pray to Allah that He grant you perseverance.
As for those who were engaged with their tongue and their pen in a war against Islam by spreading distorted ideologies and doctrines, or by spreading misguided innovations and corruption, the following is incumbent upon them:
Announce their repentance and renounce all that they used to spread in antagonism to Islam, in order that the renunciation becomes well known, and so that no one can claim to be misguided by their disowned writings. This renunciation is an obligation and is a precondition for the acceptance of repentance.
Allah says (what means):
“Save for those who repent, make amends and show clearly [what they used to say/rule wrongly], it is from those whom I accept their repentance, and I am very Forgiving, very Compassionate.”
[2:160]
The tafseer (explanation) for this verse indicates that it was revealed regarding the scholars of ahl ul-kitab (People of the Book) who used to conceal what had been revealed regarding the signs of the Prophet (peace and blessings of Allah be upon him) and the commands to believe in him.
The repentant person should now engage themselves in the spread of the truth of Islam, spending their energies in defense of its teachings, and educating people in their religion. They should use their power of speech or writing to counterattack the forces of falsehood, to expose their deceits, plans and strategies, even as he used to co-operate with them in opposing Islam, and thus become a sword in the defense of Islam. It is also binding on he who convinced another man, even if in a private meeting, against things declared haram (forbidden) by Islam, such as, for instance, taking interest, to get in touch with the person he was instrumental in changing his opinion and let him know of his own renewed enlightenment.
And Allah knows best.