Well, there is still a condition here, 'if anyone,' which is the same as 'whosoever.' If there is a condition, then there are choices to make, and the free will to respond to it. One simply believes in Christ or not. Actually, Romans 8 was specifically for those who had already received the Spirit of God. These are they who are already IN Christ and merely contrasting the life with the Spirit and the life in the flesh. 'If' presents options, offers choices or alternatives, or simply provides the ability to choose.
Romans 8:1 There is therefore no condemnation which are in Christ Jesus...
Romans 8:10 And if Christ be in you...
So this proves no inability at all.