Is the catholic religion the only religion to believe in saints?

No.

Born-againers and Baptists do as well, though the difference is that the Catholics believe only long dead people - who are claimed to perform miracles from the grave - can be saints, whereas the others believe the living are saints, without the need for performing miracles.

The Greek Word hagioi, is translated saints in the New Testament.

In the plural, it is used of believers, it designates all believers and is not applied merely to persons of exceptional holiness, or to those who, having died, were characterized by exceptional acts of "saintliness."

The verb hagiazo means to set apart and is used of the believer set apart to God and separated from the world

"Since every believer is sanctified in Christ Jesus, 1Co_1:2, cf. Heb_10:10, a common NT designation of all believers is 'saints,' hagioi, i.e., 'sanctified' or 'holy ones.' Thus sainthood, or sanctification, is not an attainment, it is the state into which God, in grace, calls sinful men, and in which they begin their course as Christians.

So the Catholic idea of saint is quite different from that of The Bible.