After the birth of Isaac, the true nature of Ishmael was revealed. Nothing of his life is known before Isaac's birth.

Even this points out a significant truth for the believer. It is not until a person receives the new nature, through receiving Christ as Saviour, that he discovers the real character of his old nature.

The discovery is a painful one and even causes some to doubt their salvation as they see the struggle taking place in their lives. However, the very fact that there is conflict is proof of salvation.

There is no conflict when there is only the old nature. But when the new nature comes in to control the life, the old nature sets up an intense conflict.

Paul referred to this conflict when he said, "For the flesh lusteth against the Spirit, and the Spirit against the flesh: and these are contrary the one to the other: so that ye cannot do the things that ye would" (Gal. 5:17).

This is the condition that results when a person receives Christ as Saviour. He receives a new nature, which is in opposition to the old nature. There is conflict between the spirit of liberty and the spirit of bondage.

Even as in the case of Ishmael and Isaac, where one had to be expelled, the believer cannot yield to both natures but must choose the one he will obey.

"For whatsoever is born of God overcometh the world: and this is the victory that overcometh the world, even our faith" (John 5:4).