God never promised to remove all trials or to give us heaven on earth. However, He has promised that the man who separates himself from the world and gives himself over to the Lord will be blessed.
Salt is necessary for life, but too much salt kills. Jesus used salt as a picture of how a small minority in the world accomplishes a great deal of good and what happens when that salt loses its saltiness.
No one should ever be forced to believe in Jesus Christ as Saviour.