You are not responsible for anyone's conversion.
You are responsible to take up your part of The Great commission, to preach in season and out of season, to have an answer for the Hope that is within you, to live before all, to soften the soil by prayer and to lead to the Lord those who are willing to meet Him.
You have no idea who will and who won't respond to the Lord. The least likely person might have been wanting Him for years, perhaps without even knowing it.
He is able to reveal Himself.
He is able to make Himself heard.
He is able to soften the most hardened heart.
He is able to forgive anything.
And, He will.