The questioner says: I fear that if I gain Fiqh (comprehension in the religion that I will not act upon it and thus fall into sin.
This is an argument that is not correct. It has no basis in the legislation nor in the intellect, and it is not permissible for him to hold this ideology. It is upon him to have a good thought about himself and be truthful with Allaah. So if he learns whilst being determined to act upon his knowledge then Allaah will pour forth upon him from His Tawfeeq and will guide him to act upon that which he knows. As for him preferring to remain upon ignorance, fearing that he will not act upon the knowledge, then this is a sign of destruction and a reason for bankruptcy in terms of legislative knowledge which rectifies the affairs of the Deen and the Dunyaa.
So it is upon the brothers to reject the likes of this ideology; and it is that which I have heard more than once from some people, while this ideology is not correct. Rather, it drags to misery and not to happiness and a wholesome life. Rather, the servant is commanded to acquire Fiqh in the religion and to learn in order to act upon this religion. If there occurs from him some shortcoming or an error, then it is upon him to repent to Allaah the Exalted, for no one is infallible from error. Rather, perpetuity in acquiring Fiqh in the religion within every time and in every circumstance, while having a truthful intention, is the behavior of the righteous, as Allaah the Glorified and High, has said:
وَالَّذِينَ اهْتَدَوْا زَادَهُمْ هُدًى وَآتَاهُمْ تَقْواهُمْ
While as for those who accept guidance, He increases their guidance, and bestows on them their piety.(Muhammad 47:17)
And He, the Mighty and Majestic, has said:
لِيَزْدَادُوا إِيمَانًا مَّعَ إِيمَانِهِمْ
…that they may grow more in Faith along with their (present) Faith. (Al-Fath 48:4)
So he who enacts the means, truthfully, sincerely, and correctly, by Allaah, he will not be destroyed. Rather, he will be happy in his Dunyaa, his Barzakh, and his Hereafter.