Actions not words
A true believer should not only believe in the God with these four attributes (Rab, Rahman, Raheem, Malik-i-yaumid-deen) with the word of the mouth; he should live the kind of life that would clearly show to the people that he does not take anyone else as his Rab, he takes God as his Rab; he does not take Zaid or Umar (X or Y) his Rab. He should be full of certainty that it is only God who rewards the actions (whether the reward is good or it is punishment); He knows the most hidden sins that a man might commit. You should know it well, that verbal claims do not mean anything whatsoever. He who takes God to be his Rab and Maalik-i-yaumiddin, in the true sense of the words, can never commit evil deeds like stealing, fornication, gambling, or other deeds like them, for, he knows that all these things are devastating and to commit them is to violate the commands of God.
The truth is that unless a man proves that he is a true believer in God and has very strong faith in Him, he cannot be the recipient of the blessings and the grace of God which are granted to those who are His near ones. The blessings that are vouchsafed to those who are near and dear to God have their sources in those people being the possessors of high certainty and strong faith; these are the people who give preference to God over everything else in the whole universe.
You must try to realise that Islam does not tantamount to mere verbal profession of faith and some “wird” and “wazaa-if” (uttering of some words repeatedly for spiritual influence); one’s practical life should be so good that he may become the recipient of the help and succour of God and he may be vouchsafed God’s generous Bounties. All the Prophets had their lives very pure, truthful, trustworthy and of high morals. They were not like the ordinary people – their fasting, payment of zakat, prayers and bowing and prostration and recitation of sura Fatiha, was not like the ordinary people, they had caused a sort of death to everything in the world; the only thing they visualised was the Being of God the Almighty; they took Him alone as their Helper and real Sustainer. It is with Him that they had real communion and it is of Him that they always thought and it is in Him that they lived their lives.
(Malfoozat, Vol. 10, pg. 37)