Thats what mankind thought at the time of Noahs flood. Note what Christ Himself stated regarding this…
37As it was in the days of Noah, so will it be at the coming of the Son of Man. 38For in the days before the flood, people were eating and drinking, marrying and giving in marriage, up to the day Noah entered the ark. 39And they were oblivious, until the flood came and swept them all away. So will it be at the coming of the Son of Man.
If you think that God will save you simply because he is just and a loving God wont kill “nice people”, then you are grossly mistaken. What we call nice people are not the same as what God calls “saints”!
There is a very specific rule about salvation and its found in Revelation 14:9-12
“If anyone worships the beast and its image, and receives its mark on his forehead or on his hand, 10he too will drink the wine of God’s anger, poured undiluted into the cup of His wrath. And he will be tormented in fire and sulfur in the presence of the holy angels and of the Lamb. 11And the smoke of their torment rises forever and ever. Day and night there is no rest for those who worship the beast and its image, or for anyone who receives the mark of its name.”
12Here is a call for the perseverance of the saints who keep the commandments of God and the faith of Jesus.
Now i believe that there will be atheists in heaven. I do not really have a sound theological support for this idea, however, the reason i believe this is because there are some people in this world who dedicate their lives to others. They may not subscribe to God, however, they do subscribe to the statement Christ made “in as much as you do it to the least of these my brethren, you do it to me” Matt 25:40
Unfortuntaly for the people here, the above does not apply to those who know better and yet refuse the whisperings of the Holy Spirit. The apostle Peter gave us a very definate answer to this one:
Acts5: 3Then Peter said, “Ananias, how is it that Satan has filled your heart to lie to the Holy Spirit and withhold some of the proceeds from the land? 4Did it not belong to you before it was sold? And after it was sold, was it not at your disposal? How could you conceive such a deed in your heart? You have not lied to men, but to God!”
9“How could you agree to test the Spirit of the Lord?” Peter replied. “Look, the feet of the men who buried your husband are at the door, and they will carry you out also.”
10At that instant she fell down at his feet and died.