Paul the Apostle lacked neither faith nor knowledge but he still had to leave behind Trophimus sick.
The problem i see with this argument is that firstly we base truth and doctrine on scriptures that declare truth and doctrine. We do not look at the bible and say trophimus was sick so God did not provide healing as a promise in the atonement on the cross because paul didnt lack faith.
That is the same thing as if we said Jesus didnt save by his blood because simon the sorcerer didnt get salvation and the apostles left him.
Bible doctrine is clear that 1)healing is part of Gods covenants 2) Healing was prophesied to be provided by the coming messiah 3) Jesus fulfilled the prophesies of him and provided with his stripes for our healing 4) Jesus healed all that came to him and said he was specifically fulfilling the verses in isaiah about him healing 5) peter specifically says that by his stripes we WERE healed.6)The bible specifically shows us and declares from gen to rev that Gods promises are by faith.7) Jesus tells us more than 2 or 3 times that whatever we ask in His name believing we shall have it.
Now when it comes to trophimus we do not have any information. We do not know who he was, why he was sick, what he was sick with, how long he was sick, just because he was sick doesnt mean he never got healed we are not told that, we do not know if it was a chastening, we do not know if it was a trial of faith that he later overcame, we do not know if he was sick because of persecution he had endured. We do not know- so we cannot use that as a reason to disbelief doctrine.
And paul could have all the faith possible but if the man himself did not have faith, ( or other things) then he may not recieve his healing.
Many times Jesus made it clear when he healed people " be it done unto you according to YOUR FAITH" he didnt say " be it done according to my faith".
We have to be very careful to believe the word of God and the promises of God and the full work of the cross and walk by faith in it. It is never ever ever ok to look at peoplein the bible our outside it and say see they arent healed, see they died, to justify a disbelief in what the bible declares because we do not know what is between God and those people. We do not know their hearts or their faith, we do not know if they doubted, or had unforigiveness or sin we just cant say but we can say what the bible says.
We cannot partake of Gods promises by being double minded and asking and then saying to oursleves " well he could say yes or no" there is no faith there only doublemindedness. All through the word saints partook of the goodness and promise of God by believing that he is faithful who promised and by believing his word and covenant no matter what things in this world looked like.