I have a question regarding shirk and major polytheism. One part of this question is intending something by deeds besides seeking pleasure of Allah. For instance, if I decide to do an action to increase my Iman, or if I read something about Islam for my interest, or I exercise for some benefit not for the sake of Allah, are such acts considered from major polytheism? I know, I should do the acts for the sake of Allah, but if I am not truly sincere, then should I not do the action?

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

Striving to increase faith, reading to gain knowledge or indulging in mental or physical exercise to strengthen the mind and body, and similar actions are not considered Shirk and they do not come under the definition of the major Shirk nor under the minor Shirk. Shirk means associating partners with Allah in His worship or Lordship or in His Beautiful Names and Attributes.

A Muslim is demanded to make every effort to increase and strengthen his faith and aspire to gain what is useful for him in this life and Hereafter. The Prophet said: “A strong believer is better and more lovable to Allah than a weak believer, and there is good in everyone, but cherish that which gives you benefit and seek help from Allah and do not lose heart.” [Muslim]

Know that even the usual acts that a Muslim performs in his daily life, if he carries them out with the intention of Taqwa, to avoid what is unlawful, intending also that if they were not lawful he would not perform them, then if he performs them with the above intention, he will be rewarded for those usual acts.

The Prophet said: “…. even in having sex with one's wife is a Sadaqah (an act of charity). They got astonished and asked, 'O Prophet of Allah! One of us fulfills his sexual desire and gets reward for that?' The Prophet said: “Don't you know that if he makes illegal sex, he commits sin? Likewise, when he makes it in a lawful way, he will be rewarded.” [Muslim]

Allah knows best.