The Spirit gives life; the flesh counts for nothing. The words I have spoken to you are spirit and they are life.
The Spirit gives life and without the Spirit, a lost man can do nothing spiritual. His spirit is dead. EVERYTHING a lost man does is in the flesh, and as Jesus just said, the flesh counts for nothing. That is why a lost man, i.e. he who is in the flesh, can do nothing pleasing to God (Romans 8:8) because the flesh is all he has (and it counts for nothing).
So if a lost man can do nothing pleasing to God, how can he look to Jesus? How can he accept Jesus? How can he Believe God? How can he repent? How can he understand the things from the Spirit of God? The answer to all of those is - HE CAN’T! The flesh is all he has (and it counts for nothing). HE’S DEAD. HE CAN’T PLEASE GOD!
That is why God FIRST quickens the dead spirit in a lost man (saving him) which enables him to do spiritual things. This is the spiritual birth Jesus spoke of in John 3:5-6 and no more than a baby can cause itself to be born, a man can’t “cause” himself to be spiritually born. After God quickens the dead spirit in a lost man, the redeemed man can NOW please God and believe, repent, confess, etc... The saved man WILL now come to Christ (John 6:37), no ifs ands, or buts. Praise God for His Holy, inspired, infallible, inerrant, Word.