The best thing that you could ever tell a sinner is to warn them about a place called hell and telling them how to avoid this place. Love warns. A few years before I was born again someone I went to school with for years who got saved/born again told me I was going to hell if I was not born again not only once but twice he told me that on two different occasions and of course during that time I didn't mock him but I did not take him seriously but a few years later on I did get saved radically saved through the conviction of sin and once I was saved my mom told me that she had been praying for me for 16 years and then during that moment where I got saved in 1994 at the age of 31 the Holy Spirit made it very clear to me that if I died in my present condition I would not go to heaven and I knew that hell was the other option, the Holy Spirit made that very clear to me and I will be eternally grateful to God for what he did for me on that day, you mentioned love your neighbor and your enemy and that's very true but what about the rest of the Bible what about the rest of the New Testament and what it has to say unless you're a cherry picker which the church is full of cherry pickers also meaning they are really good at having selective hearing.