I am a Muslim but have not been active, Astaghfirullah. I am changing but I want to ask will a Christian, a Jew or a Hindu for that matter enter Jannah because he lived up to his religion and so on, or will he go to hell? I am not sure.

Praise be to Allah, the Lord of the World; and may His blessings and peace be upon our Prophet Muhammad and upon all his Family and Companions.

We pray to Allah, The Exalted, to grant you success to do good deeds and to help you avoid every misdeed.
Know that Allah, The Exalted, is the Creator of all creatures and He Who provides them with the means of subsistence; to Him belongs the command; He is the irresistible, above His slaves, and He is the All-Wise, Well-Acquainted with all things.
He has tried His slaves with the Book (Qur'an) He revealed and the Messenger He Sent. So, whoever believes and obeys, he will be rewarded with Paradise; while whoever disbelieves and disobeys will be punished with Hell-Fire.
He, The Exalted, Says: And whoever seeks a religion other than Islâm, it will never be accepted of him, and in the Hereafter he will be one of the losers.} [3: 85].
The Prophet (Sallallahu Alaihi wa Sallam) said: "All my followers will go to heaven, except those who defy me. His companions said: 'O Allah's Messenger! Who will be such people?' The Prophet (Sallallahu Alaihi wa Sallam) said: "One who obeys me will enter Paradise, and the one who disobeys me defies me (will not enter Paradise" [Reported by Imams al-Bukhari and Ahmad ].
This means that whoever (i.e. a Jew, Christian, Hindu, etc.) disbelieves in Allah, The Exalted, or His Messenger (Sallallahu Alaihi wa Sallam), will enter the Hell-Fire and remain there forever. Then, if Jews and Christians believe in the teachings of their Prophets and follow them faithfully, they should have faith in Muhammad (Sallallahu Alaihi wa Sallam), since their Prophets informed them of his coming (Sallallahu Alaihi wa Sallam).
For more details, please read the Fatwa: 83348.
Allah knows best.