You can gain eternal life by believing in Jesus Christ, and living a Christian lifestyle.
Three bible versus: "For God so loved the world that he gave his one ans only son, so that we may not perish but have eternal life." - John 3:16
"I write these things to you who believes in the in the name of the Son of God so that you may know that you have eternal life." - 1 John 5:13
"For it is through grace that you have been saved, through faith--and this is not from yourselves, it is a gift from God." - Ephesians 2:8
Christians believe in behaving yourself to get to heaven, some branches believe in purgatory, others don't. Judaism doesn't really have too much to say on the afterlife. Buddhist believe that you die then get reborn, their goal is to stop it for themselves. Islam believes in a "soul sleep" until judgement day. They believe that non-believers can get to heaven if they spend time in purgatory.
General intelligence refer to general cognitive ability of human mind to solve logical and reasoning problems, complex data problems and verbal reasoning test. This test is generally required after secondary school to get admission in high school. Its meant to test mental capacity to solve unseen reasoning questions.