Baptist Catechism ~ 33

How are we made partakers of the redemption purchased by Christ?
A.~ We are made partakers of the redemption purchased by Christ, by the effectual application of it to us, by His Holy Spirit.
(John 3:5,6; Titus 3:5,6)
Why must we be Born Again.
Jesus answered and said unto him, Verily, verily, I say unto thee, Except a man be born again, he cannot see the kingdom of God.
4 Nicodemus saith unto him, How can a man be born when he is old? can he enter the second time into his mother's womb, and be born?
5 Jesus answered, Verily, verily, I say unto thee, Except a man be born of water and of the Spirit, he cannot enter into the kingdom of God.
6 That which is born of the flesh is flesh; and that which is born of the Spirit is spirit.