Let us assume that every person carries sin within himself since birth. Will not God, the merciful Lord, simply forgive him this sin?

Answer: See the second half of the answer to question 5 and 6. Once again: It was God's decision not to acquit humanity simply by simply exercising His authority. Rather, He wanted to save humanity by becoming man Himself and becoming like us in all except sin. At the same time, He wanted to enable us, by the power of the Holy Spirit, to become His sons and daughters for all eternity, the brothers and sisters of His son, Jesus Christ.