Read the context of spiritual gifts and functions in the Body again and think about all the ways "faith" is discussed.
The way I read the Text, God gave us the functions of perceptions, reasoning, choice, belief, infused into us knowledge of His existence, power, divinity, justice, righteousness, then identified His Son to us and what He has provided for us in His Son and thereby has provided not only the capacity to believe but the information He requires us to believe and He draws men to His Son by teaching them.
When I see this measure of faith in the context of spiritual gifts and functions of gifts in the Body for the benefit of the entire Body, I'm not seeing a measure of Faith to believe in His Son, but to function in the Body of Christ.