God did not refuse to bless Ishmael, but He caused Abraham to clearly understand that
the covenant would be established with Isaac, who was not yet born. Ishmael was not to
be an heir with Isaac. The Scriptures build on this principle in showing that the flesh
(Ishmael) cannot be heir with the Spirit (Isaac).
In the New Testament, the apostle Paul referred to Ishmael and Isaac and drew a
parallel to Christians. Paul was emphasizing that the Christian is made mature through
the freedom of the Spirit and not through the bondage of the Law. He wrote:
"Nevertheless what saith the scripture? Cast out the bondwoman and her son: for the
son of the bondwoman shall not be heir with the son of the freewoman. So then,
brethren, we are not children of the bondwoman, but of the free" (Gal. 4:30-31).
Paul continued the parallel in Galatians 5 when he said, "This I say then, Walk in the
Spirit, and ye shall not fulfil the lust of the flesh. 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" (vv. 16-17). In this same chapter, Paul also wrote:
"They that are Christ's have crucified the flesh with the affections and lusts. If we live in
the Spirit, let us also walk in the Spirit" (vv. 24-25).
For I know that in me (that is, in my flesh, dwelleth no good thing: for to will is present
with me; but how to perform that which is good I find not (Rom. 7:18).