Call to good, and be patient if they don’t listen. Strive to be humble and remember the time when you were lost and misguided, and it was purely by His Mercy & Grace that you could walk on the Path of Light.
Most of all, refrain from passing conclusive judgements on others! We have not been made lords over others to decide their fate on the Day of Judgement.
It says in al-Saheeh that a man said: “By Allah, Allah will not forgive So and so. Allah said: ‘Who is the one who swore by Me that I will not forgive So and so? I have forgiven So and so and I have cancelled out your good deeds.”