There r thousend of reasons
first the nature I cant belvie someone could think that everything had happened random , the laws of physics r so perfectly established, that one must say taht the one taht created that laws of physics n everything is a very intelligent been.
There most be an logical order , if everyone in teh whole world could do absolutely whatever they want , this means i can be the more evil person n if i have a pleasing death it ll end all there n i ll be free from a punish, its nonsense, this means that u can kill anyone, thousend or millions like stalin n have a pleasing death n u wont be punish at all , if thats the true I cant understand how we were all created to do that whithout consequences.
also that I feel the presence of God , but its difficult to really feel him , when he do a miracle or he show himslef he ll hide after ,cause he want us to belive with our own faith, not because of miracles.
God is also with everyone that request him , however he cant talk to u clearly until u get a pure heart cause God cant talk to someone if u could sin awfully the next day.
Another reason is the abundand miracles that happen, near me n everywhere ; the incorrupts the saints , the apparitiosn of the blessed virgin, the miraculous healing , the phenomens, the exorcists, etc
and another reason is taht I didnt used to go to church , afterwards i had an illnes on my liver n I started to go to church more often n i talked to the priest n he made me the signal of teh cross n he gave me his blessing n i felt a great healing on my liver the pain had stopped completely for some hours , I think taht is a message that means i shouldnt go to church jsut one time but every sunday to get better, or its a signal that God is with me througout everything that happened to me in my illnes , that day i discovered that God is so close every second, dispite I dotn feel his presence at all.
Also the miracles that happen in Latin america n on poor places , there had been several miracles on my parish, there r statues that cry , apparitions of teh blessed Mother etc.
there had been many saints that had have amazing gift from God bi - location , levitation and other gift , some bodys of deceaced saints had became incorruptible after 400 years of their deaths.
Also the gospels are historic , if someone dotn belive the gospels that person dotn ahve the right to believe in any ancient history, cause the gospels are more historic than any document of that time.
Another reason is the shroud of Turin. Its is the shroud in which Jesus was covered after his death. There have been alot of slanders about the shroud of turin but I had studied it , and the image of a man in the shrourd of turin is a image that is burned in fire and radiation , “this assures everyone the resurection of Jesus” many atheist tried to debunk this relic, saying that it was a medieval painting of the 13 century , but the nasa had discovered that the image of the man in that shroud was made by fire and the NASA made a tridimentional sculpture of the image of the man in that shroud, no painting can be a tridimentional sculpute, also this relic has microscopic pollen of palestine from the I st century.
there are a lot more reasons to belvie in God…