At death the spirit of man does not cease to exist or become unconscious. The dead will be raised bodily either to eternal life or eternal condemnation. Heaven & hell are realities, in fact the Lord Jesus spoke at length about hell emphasising its awful reality. Heaven is where God is, and hell is where God is not.
This is what the Bible says about Heaven & Hell -
“Enter ye in at the strait gate: for wide is the gate, and broad is the way, that leadeth to destruction, and many there be which go in thereat: because strait is the gate, and narrow is the way, which leadeth unto life, and few there be that find it.” Matthew 7: 13-14
“For the Lord himself shall descend from heaven with a shout, with the voice of the archangel, and with the trump of God: and the dead in Christ shall rise first: then we which are alive and remain shall be caught up together with them in the clouds, to meet the Lord in the air: and so shall we ever be with the Lord. Wherefore comfort one another with these words."
1 Thessalonians 4: 16-18
"And I saw a great white throne, and him that sat on it, from whose face the earth and the heaven fled away; and there was found no place for them.
And I saw the dead, small and great, stand before God; and the books were opened: and another book was opened, which is the book of life: and the dead were judged out of those things which were written in the books, according to their works.
And the sea gave up the dead which were in it; and death and hell delivered up the dead which were in them: and they were judged every man according to their works. And death and hell were cast into the lake of fire.
This is the second death. And whosoever was not found written in the book of life was cast into the lake of fire.” Revelation 20: 11-15