Another interesting construction is found at 1 Timothy 1:16
The Greek word translated "for" eternal life is "eis" so perhaps the idea is for those who are going to believe in or on Him into eternal life. Our eternal life begins when we are united with Christ which occurs when we are transferred into Christ. The result of God crediting our belief in Christ is eternal life!16 But because of this I was shown mercy, in order that in me foremost, Christ Jesus might demonstrate his total patience, for an example for those who are going to believe in him for eternal life. (LEB)