As long as I can believe my wife is the most beautiful I can flirt with other women she will not mind!
As long as I believe Obama is a Muslim I am a good republican, I do not have to pay party dues or go out and vote!
As long as I believe that taxes ought to be paid, IRS will not bother!
As long as I believe that I need to study for the examination I can have a perfect score, I do not need to attempt the exam!
As long as I can believe this car is yours I can keep using your car without asking!
As long as I believe one should speak the truth, I can keep on lying!
And as long as I can believe Jesus or at least Moses died for the Muslims and not the Christians, I do not have to become a Christian for my salvation. This is my Muslim Sola gratia as opposed to the standard Protestant one, and I am sticking to it and going to heaven, or is it fool’s paradise or Alice’s wonderland?
Now that you know my personal Muslim Sola gratia, here is the standard Christian version of it, as described in Wikipedia:
Sola gratia is one of the five solas propounded to summarize the Reformers’ basic beliefs during the Protestant Reformation; it is a Latin term meaning grace alone. Protestant reformers believed that this emphasis was in contradistinction to the teaching of the Roman Catholic Church, though the Catholic Church had explicitly affirmed the doctrine of sola gratia in the year 529 in the Council of Orange, which condemned the Pelagianism heresy. … During the Reformation, Protestant leaders and theologians generally believed the Roman Catholic view of the means of salvation to be a mixture of reliance upon the grace of God, and confidence in the merits of one’s own works performed in love, pejoratively called Legalism. The Reformers posited that salvation is entirely comprehended in God’s gifts (that is, God’s act of free grace), dispensed by the Holy Spirit according to the redemptive work of Jesus Christ alone. Consequently, they argued that a sinner is not accepted by God on account of the change wrought in the believer by God’s grace, and indeed, that the believer is accepted without any regard for the merit of his works—for no one deserves salvation, a concept that some take to the extreme of Antinomianism.
To assure you that I am not making it up let me quote Lutheran theology about Sola gratia, from Encyclopedia Britannica also,which applies to all forms of classic Protestantism:
Theologically, Lutheranism embraces the standard affirmations of classic Protestantism—the repudiation of papal and ecclesiastical authority in favour of the Bible ( sola Scriptura ), the rejection of five of the traditional seven sacraments affirmed by the Catholic Church, and the insistence that human reconciliation with God is effected solely by divine grace ( sola gratia ), which is appropriated solely by faith (sola fide), in contrast to the notion of a convergence of human effort and divine grace in the process of salvation. 
Dr. Phillip Cary is Professor of Philosophy at Eastern University in St. Davids, Pennsylvania, where he is also Scholar-in-Residence at the Templeton Honors College. After receiving his B.A. in English Literature and Philosophy from Washington University in St. Louis, Professor Cary earned his M.A. in Philosophy and Ph.D. in Philosophy and Religious Studies from Yale University.
Professor Cary is a recent winner of the Lindback Award for excellence in undergraduate teaching at Eastern University. He has also taught at Yale University, the University of Connecticut, and the University of Hartford. As the Arthur J. Ennis Post-Doctoral Fellow at Villanova University, he taught the nationally recognized undergraduate Core Humanities seminars on ancient, medieval, Renaissance, and modern thought. He writes in his Course Guidebook for the series, the History of Christian Theology:
Reformed and Lutheran theology agrees on three characteristically Protestant sola statements against Roman Catholic theology: sola fide, sola gratia, and sola scriptura. Sola fide (‘faith alone’) means we are justified by faith alone, apart from works of the Law. Catholics also teach justification by faith, but that don’t add ‘alone.’ Good works are also required for salvation, because we are justified by ‘faith working by love’ (Gal. 5:6). The ‘alone’ here excludes good works, particularly works of love, which should be done but make no contribution to justification. Protestants agree that faith works through love, but make this part of sanctification, not justification. They say it contributes nothing to ultimate salvation. For Protestants, faith necessarily results in good works, but good works do not contribute anything to salvation. Sola gratia (‘grace alone’) means we can never do anything to earn or deserve salvation. The word ‘alone’ here excludes merit. Even after grace and faith, our works earn no merit before God. By contrast, for Catholics, our good works, which are the result of grace, do indeed have merit in God’s sight. Whereas Protestants refuse to believe in any merits of their own, Catholics insist especially on the merits of the saints. 
The Islamic teaching about salvation is in line with human psychology and is based on belief as well as actions and is encapsulated in one of the shortest chapters of the Holy Quran:
In the name of Allah, the Gracious, the Merciful. By the fleeting Time, surely, man is in a state of loss, except those who believe and do good works, and exhort one another to accept truth, and exhort one another to be steadfast. (Al Quran 103:1-4)
Incidentally, the New Testament has exactly the same teaching, perfectly in line with the Quranic teaching,in the Book of James:
What good is it, my brothers and sisters, if someone claims to have faith but has no deeds? Can such faith save them? Suppose a brother or a sister is without clothes and daily food. If one of you says to them, ‘Go in peace; keep warm and well fed,’ but does nothing about their physical needs, what good is it? In the same way, faith by itself, if it is not accompanied by action, is dead. But someone will say, ‘You have faith; I have deeds.’ Show me your faith without deeds, and I will show you my faith by my deeds. You believe that there is one God. Good! Even the demons believe that—and shudder. You foolish person, do you want evidence that faith without deeds is useless? Was not our father Abraham considered righteous for what he did when he offered his son Isaac on the altar? You see that his faith and his actions were working together, and his faith was made complete by what he did. And the scripture was fulfilled that says, ‘Abraham believed God, and it was credited to him as righteousness,’ and he was called God’s friend. You see that a person is considered righteous by what they do and not by faith alone. In the same way, was not even Rahab the prostitute considered righteous for what she did when she gave lodging to the spies and sent them off in a different direction? As the body without the spirit is dead, so faith without deeds is dead. (James 2:14-26)
If you have not still understood the point then a careful evaluation of different presentations of Sola gratia by Luther, Calvin, Andreas Ossiander (1489-1552) or the Catholic Church may do the trick for you and push you in the right direction. While you are at it also study the so called heretics Pelagius and Celestius.
We can choose to believe anything, but are we creating fool’s paradise! The main defense we humans have against fallacy is reason. We should use it obsessively rather than obsessing over medieval fallacies created by St Paul and Martin Luther.