To many the Tulip mnemonic is all there is to Calvinism but in reality all TULIP was is a specific response to specific representations.
In the 17th century a Dutch theologian called Jacob Aminius put forward arguments that centered on the freedom of mans will to approach God, Arminius always claimed his orthodoxy but in the years following his death his followers became more bold and remonstrated their position under five separate theological points, a great synod was held at Dordt that considered the Remonstrants five points condemning these points in the promulgation of the Canons of Dordt that answered the Remonstrants five points with five counter points that came to be known as the five points of Calvinism, thereafter to be remembered by the mnemonic TULIP.
The five points of Calvinism are therefore not a summary of Calvinism but a specific response to five specific points. That being said the five points (TULIP) do form a systematic and coherent exposition of the relationship between man and God, the five points begin to unravel if any one is rejected.
Original sin means that man is unable to approach God or to do anything but sin, his will being in bondage to sin.
God chooses who are his elect according to his own sovereign will, not due to any act or quality in the person or due to any foreknowledge of that persons response to the gospel.
Jesus died only for the elect, who had been predestined to salvation before the creation of the world, not for the mass of humanity. This is perhaps better termed definite atonement in that Christ atoned definitely and with certainty for the elect. If Christ died for your sins then you are forgiven and the punishment of your sins are satisfied in the death of Jesus, if it were possible for you to reject Christ then this also would be forgiven. If any element of your salvation relied on your own lack of sin or faith then you would always fail and Christ's death would achieve nothing. This is not to limit in any way the power of Jesus's sacrifice, for his own good and just reasons God has decided to show undeserved mercy to those he elects to his people and while the atonement was sufficient for all it is efficient only for the elect.
Regeneration cannot be resisted, we are raised from death to life and by the grace of God this new life is certain.
Perseverance of the saints
God will see to it that his elect will be preserved, it is by the will of God that his elect are saved and the elect will be protected by the will of God from falling away.