“For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life.” John 3:16
But that way is open to everyone:
So, how do you become a Christian?
Through an act of faith. Pray to God, asking Him to forgive your sins and confessing that you believe in Him and in the sacrifice of His Son Jesus and that you want to live your life for Him.
“If you confess with your mouth that Jesus is Lord and believe in your heart that God raised him from the dead, you will be saved.” Romans 10:9