By grace through faith. Even your faith is a gift from God (if you do in fact have a genuine faith).
Jesus Christ promised that all who believe in Him shall not perish but have everlasting life. In Him we have redemption through His blood, the forgiveness of our trespasses, according to the riches of His grace and not by any merit of our own.
As it is written, "You did not choose me, but I chose you and appointed you that you should go and bear fruit and that your fruit should abide, so that whatever you ask the Father in my name, he may give it to you." (John 15:16 ESV)
