What if my father was the richest man in the world, and he gave all his wealth to me. What if I met someone so poor they would literally die without help. Food, shelter, etc. What kind of human being would I be if I stood by and watched them die, doing nothing?
That's exactly how it is when a Holy Spirit filled, Christ following, Father loving, faithful believer meets an unredeemed sinner. Our Father which art in Heaven, has wealth unimaginable - he is so wealthy He can purchase our souls and keep us from suffering eternal damnation.
I'm actually one of His sons, I know Him personally and I can have adoption papers drawn up for you, if you'd like to become a part of His family too. He's so wealthy, He can adopt literally everyone on earth and take good care of them all. But you must agree to His terms of adoption. Love him and obey him. It's that simple.
Yes, if I selfishly kept this knowledge to myself - what kind of man would that make me? If I meet you, and realize you have no idea who your real father is, if I know you are so poor you cannot purchase eternal food and drink, to revive your spirit and save your soul, if I see you are a slave who cannot afford to buy their freedom, and I have the wealth needed to save you and set you free, and I do nothing, what kind of man would that make me?