...He staggered not at the promise of God through unbelief but was strong in faith, giving glory to God (Romans 4:19-20).

But Abraham disregarded all contrary situations and was strong in faith! He had seen in his spirit the son that was promised, and that picture was more real than his old frail body and that of his wife. He maintained his confession and sure enough, Isaac was born. Now, those who might have called him “foolish old Papa Abraham” must have been speechless when Isaac showed up.
Understand that you can never be a fool for faith! Whenever you take steps of faith in God and His eternal Word your action will certainly pay off. The challenge some folks have sometimes is that they mistake “believing” for “faith.” Faith is the title-deed of unseen realities (Hebrews 11:1). Faith is the proof that what you hoped to have is yours now.
Abraham was not calling himself, “Father of many” to get God to give him a son, or to convince himself of what God said! He called himself that name because he had confidence in his spirit that he already had a son, though it hadn’t materialized physically. That’s faith. When acting in faith, you no longer try to convince yourself or convince God; rather, you know in your spirit that you have it made— you’ve got what the Word says is yours.
It doesn’t matter today who is making jest of you or mocking you for your faith; you have the evidence-God’s Word, that what He says belongs to you belongs to you, therefore refuse to let go. It’ll only be a matter of time before it shows up physically, and it’ll be your turn to laugh in celebration, for you can never be a fool for faith.