Because the Lord Jesus Christ said so.
Because you have a sinful nature. The nature we all receive from Adam is fallen, corrupt and totally depraved. God says the heart of man is desperately wicked and deceitiful above all things. With this old nature you could not enjoy yourself in Heaven hereafter. Heaven is a holy place. When you are born again, God gives you a holy nature that you might enjoy yourself in Heaven, a holy place.
Because you cannot save yourself. "For by grace are ye saved through faith; and that not of yourselves: it is the gift of God: not of works, lest any man boast," (Eph 2:8,9). "Not by works of righteousness which we have done, but according to His mercy He saved us," (Titus 3:5). Now don't skip over these two quotations from God's Holy Word. Read them again and again until the truth grips you. You cannot save yourself-you MUST be born again.
From: Bible Tracts, INC
