Jesus says you have to enter through the strait gate to be saved.
 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 [KJV])
What is the strait gate?
1 Christ is the doore and the good Shepheard. — KJV, Chapter summary of John 10
We see that Christ is the door.
So how do you enter through the door?
 Jesus said unto her, I am the resurrection, and the life: he that believeth in me, though he were dead, yet shall he live:  And whosoever liveth and believeth in me shall never die. Believest thou this? (John 11:25-26 [KJV])
Faith alone in Christ alone.
Salvation is easy. But its not automatic. That is, a lot of people don't believe.
Hebrews 4:2 KJV  For unto us was the gospel preached, as well as unto them: but the word preached did not profit them, not being mixed with faith in them that heard it.
They can here the gospel but Christ is hidden to them. Its by faith that we are saved and faith in itself is a supernatural thing.
It is possible to be a sinner and saved.