Do people who believe in scientology believe in other religions?

Scientology is supposedly a religion yeah? So does that mean they dint believe in Christianity or Islam or Jesus? Do they celebrate Christmas then?

Scientology is not a religion, it is a cult based on a fictional story.

Often no. However, one can know for sure that Jesus is the Son of God by praying the rosary regularly. See the following promises.

The rosary is explained here:
http://www.medjugorje.org/rosary.htm

The fifteen promises of Mary to Christians who recite the rosary:
1. Whoever shall faithfully serve me by the recitation of the Rosary shall receive signal graces.
2. I promise my special protection and the greatest graces to all those who shall recite the Rosary.
3. The Rosary shall be a powerful armor against Hell, it will destroy vice, decrease sin, and defeat heresies.
4. It will cause virtue and good works to flourish; it will obtain for souls the abundant mercy of God; it will withdraw the hearts of men from the love of the world and its vanities and will lift them to the desire of eternal things. Oh, that souls would sanctify themselves by this means.
5. The soul which recommends itself to me by the recitation of the Rosary, shall not perish.
6. Whoever shall recite the Rosary devoutly, applying himself to the consideration of its sacred mysteries, shall never be conquered by misfortune. God will not chastise him in His justice, he shall not perish by an unprovided death; if he be just, he shall remain in the grace of God and become worthy of eternal life.
7. Whoever shall have a true devotion for the Rosary shall not die without the Sacraments of the Church.
8. Those who are faithful to recite the Rosary shall have during their life and at their death the light of God and the plenitude of His graces; at the moment of death, they shall participate in the merits of the saints in Paradise.
9. I shall deliver from Purgatory those who have been devoted to the Rosary.
10. The faithful children of the Rosary shall merit a high degree of glory in Heaven.
11. You shall obtain all you ask of me by the recitation of the Rosary.
12. All those who propagate the Holy Rosary shall be aided by me in their necessities.
13. I have obtained from my Divine Son that all the advocates of the Rosary shall have for intercessors the entire Celestial Court during their life and at the hour of death.
14. All who recite the Rosary are my sons, and brothers of my only Son, Jesus Christ.
15. Devotion to my Rosary is a great sign of predestination.

God bless!
Dave

There are Scientologists that are also other religions too. I know of Scientologists who are Christians, Jews, Buddhists, Hindus and Muslims.

Some Scientologists still subscribe to there previous religion, they combine the 2, while others identify Scientology as there only religion.

Some Scientologists celebrate Christmas, some don't, it isn't an issue in Scientology.

There are Scientologists who believe that they can practice both religions. As Scientology doesn't expect them to pray to any specific God, it does not immediately seem contradictory. I'm sure Christian/Scientologist hybrids would celebrate Christmas.

However, when followers of Scientology reach OTIII the nature of the origins of Scientology are slowly revealed. Their beliefs on creation run directly contradictory to the creation stories of all major religions. At this time it becomes sort of an all or nothing situation. You can't both believe in Christ and that there was once an Evil Lord Xenu.

Ps: Scientology isn't a religion, it is a cult. And a murderous and dangerous one at that. Check sources for support of all statements.