TULIP and me

TOTAL DEPRAVITY

Also called "radical depravity" and "total inability", this point means that every person is corrupt and sinful throughout in all of his or her faculties, including the mind and will. Thus, no person is able to do what is truly good in God's eyes, but rather, everyone does evil all the time. As a result of this corruption, man is enslaved to sin, rebellious and hostile toward God, blind to truth, and unable to save himself or even prepare himself for salvation.
Gospel Outreach on Total Depravity

UNCONDITIONAL ELECTION

Election means "choice." God's choice from eternity past, of whom he will bring to himself, is not based on foreseen virtue, merit, or faith in the persons he chooses but rather is unconditionally grounded in his own sovereign decision. This does not mean that final salvation itself is unconditional; rather, it means that the condition upon which salvation hinges (faith) is graciously given to those whom God has unconditionally chosen to receive it.
Gospel Outreach on Unconditional Election

LIMITED ATONEMENT

Also called "particular redemption" or "definite atonement", the doctrine of the limited atonement is the teaching that Jesus's atonement was definite and certain in its design and accomplishment. It teaches that the atonement was intended to render complete satisfaction for those and only those whom the Father had chosen before the foundation of the world. Calvinists do not believe that the atonement is limited in its value or power (if the Father had willed it, all the people of all generations could be saved), but rather they believe that the atonement is limited in that it is designed for some and not all.
Gospel Outreach on Limited Atonement

IRRESISTIBLE GRACE

Also known as "effectual grace", this doctrine does not hold that every influence of God's Holy Spirit cannot be resisted but that the Holy Spirit is able to overcome all resistance and make his influence irresistible and effective. Thus, when God sovereignly purposes to save someone, that individual cannot successfully resist him.
Gospel Outreach on Irresistible Grace

PERESVERANCE OF THE SAINTS

Also called the "preservation of the saints" or "eternal security," the fifth point teaches that those whom God has called into communion with himself will continue in faith until the end. Those who apparently fall away either never had true faith to begin with or will return. This is slightly different from the "once saved, always saved" view prevalent in some evangelical churches in which, despite apostasy or unrepentant and habitual sin, the individual is truly saved if he or she had truly accepted Christ in the past; in traditional Calvinist teaching, apostasy by such a person may be proof that they never were saved.
Gospel Outreach on Perseverance of Saints

Doctrines of Grace by John Piper - an excellent must-listen-to collection of sermons.

Now the question: why do I believe like that?
And the answer: because it IS the Gospel, Grace of God plus/minus nothing. I had struggled with this for a long time, but there simply is no other faith than acknowledging God as my Supreme Lord and Savior. And that is it, plain and simple.
Of course, the other gospels are pleasing to the ear, but far from God and His true nature. I have made it my evening custom to listen to some debates between Calvinists and Arminians, as well as between 'cheap grace'-believers and 'Lordships'. There is no doubt in my mind which arguments are biblical and water-proof, and which are just wishful thinking and human invention.
Of course, accepting the Bible takes off all human pride of you, and not everybody is ready to do that.
I pray that God with His Grace opens more eyes to these truths. the road is narrow, but not impossible to walk on.