17.Why did Christ become a curse for us?

So that the Divine blessing of righteousness, of fellowship with God, could be given to the Gentiles.

That which no Gentile could have earned by his own righteous behaviour was earned for him by the obedience of Christ.

When the Gentile ceases from his own attempts to earn right standing with God and accepts the righteousness that Christ has earned for him, the Divine curse that would have fallen on him falls instead on Jesus, and the righteousness of Christ is conferred on the Gentile believer.