Just as the child of the flesh persecuted the child of promise, the spiritual children of God can expect persecution from those living according to the flesh.
Abraham's experiences teach us not to try to force God's will. When any sin or self-will is involved, the fruits of such an endeavor will be bitter.
We earn God's favor by obedience; there is a direct tie between submission to His will and His favor. The more one submits, the more favor and grace accrues.
Abraham embodied living by faith. Through perpetually living in a tent, he demonstrated his complete trust and reliance upon God.