To me, true faith is based on knowledge that came from Allah. Yes i do agree that we claim we believe, but many of us actually don't believe. Does faith fluctuate? or is it because of our ignorance? Are we hypocrites knowingly? Why what we do or say often leads to SHIRK or disbelief.....You have exquisitely clarified who can be called believers as well as what we should do to be believers.
Whom did we actually fear more – Allah or other things like poverty, loss of face amongst peers or bosses? Allah tests each individual, i.e. checks the importance and the priority we give Him given the situations in our day-to-day lives---yes you are absolutely right. But one can listen to peers or bosses or parents until and unless the commandments don't go against those of Allah and Muhammad (sm). Opinions, views n perception vary; it's better if we accept them n live in consensus without making chaos n FITNAH, which are much worse than slaughter as The Qur'an says.
Allah has told us that He will forgive all sins for the one who repents to Him. He says (interpretation of the meaning):“Say: ‘O My slaves who have transgressed against themselves (by committing evil deeds and sins)! Despair not of the Mercy of Allah, verily, Allah forgives all sins. Truly, He is Oft‑Forgiving, Most Merciful’†[al-Zumar 39:53]
This includes all sins, even shirk. Whoever repents, Allah will accept his repentance.
With regard to repentance from shirk in particular and the acceptance thereof, Allah says (interpretation of the meaning):
“And those who invoke not any other ilaah (god) along with Allah, nor kill such person as Allah has forbidden, except for just cause, nor commit illegal sexual intercourse and whoever does this shall receive the punishment.
69. The torment will be doubled to him/her on the Day of Resurrection, and s/he will abide therein in disgrace;
70. Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allah will change their sins into good deeds, and Allah is Oft‑Forgiving, Most Merciful†[al-Furqaan 25:68-70]
Allah mentions the kufr and shirk of the Christians, then calls them to repent. He says (interpretation of the meaning):
“Surely, disbelievers are those who said: “Allah is the third of the three (in a Trinity).†But there is no Ilaah (god) (none who has the right to be worshipped) but One Ilaah (God —Allah). And if they cease not from what they say, verily, a painful torment will befall on the disbelievers among them.
74. Will they not turn with repentance to Allah and ask His forgiveness? For Allaah is Oft‑Forgiving, Most Merciful†[al-Maa'idah 5:73-74]
No matter how great the sin, the forgiveness, generosity and kindness of Allah is greater.
What we, muslims have to do is to turn to Allah, regret what we did and resolve not to do it again. Then receive the glad tidings of the bounty and mercy of Allah, for Islam wipes out whatever sins came before it, as the Prophet (peace and blessings of Allaah be upon him) said to ‘Amr ibn al-‘Aas (may Allah be pleased with him): “O ‘Amr, do you not know that Islam wipes out whatever came before it.†Narrated by Muslim, 121; Ahmad, 17861.
And the Prophet (peace and blessings of Allaah be upon him) said: “The one who repents from sin is like one who did not sin.†Narrated by al-Tirmidhi and classed as hasan by al-Albaani.
If a person repents to Allah, Allah accepts his/her repentance and forgives him/her. Allah says (interpretation of the meaning):
“And He it is Who accepts repentance from His slaves, and forgives sinsâ€[al-Shoora 42:25]
“And verily, I am indeed forgiving to him/her who repents, believes (in My Oneness, and associates none in worship with Me) and does righteous good deeds, and then remains constant in doing them (till his death)†[Ta-Ha 20:82]
We have to think well of our Lord and hope that He will accept our repentance, for Allah says, “I am as My slave thinks I am.†A hadeeth qudsi narrated by al-Bukhaari, 7066; Muslim, 2675. According to Ahmad with a saheeh isnaad: “I am as My slave thinks I am, so let him think whatever he wants.â€
With regard to strengthening our faith, this may be done in many ways, such as the following:
1 Remembering Allah a great deal, reading His Book and sending a great deal of blessings upon His Prophet (peace and blessings of Allah be upon him). We should read Qur’an a great deal and ponder its verses, for in that there is healing for what is in our heart, if Allah wills. Allah says (interpretation of the meaning):
“And We send down of the Qur’an that which is a healing and a mercy to those who believe†[al-Isra’ 17:82]
2 Regularly offering the obligatory prayers on time and offering a lot of naafil prayers, so that one may attain the love and support of Allah as it says in the hadeeth: “Whosoever shows enmity to someone devoted to Me, I shall be at war with him. My servant draws not near to Me with anything more loved by Me than the religious duties I have enjoined upon him, and My servant continues to draw near to Me with supererogatory works so that I shall love him. When I love him I am his hearing with which he hears, his seeing with which he sees, his hand with which he strikes and his foot with which he walks. Were he to ask [something] of Me, I would surely give it to him, and were he to ask Me for refuge, I would surely grant him it.†Narrated by al-Bukhaari, 6137.
3 Keeping company with good people who will help us to worship and obey Allah and discourage us from disobeying Him.
4 Reading biographies of righteous people among the scholars, ascetics (zaahids), devoted worshippers and those who repented. Allah narrated the biographies of the prophets in the Qur’an to make the heart of his Prophet (peace and blessings of Allah be upon him), and the believers with him, steadfast. Allah says (interpretation of the meaning):
“And all that We relate to you (O Muhammad) of the news of the Messengers is in order that We may make strong and firm your heart thereby. And in this (chapter of the Qur’aan) has come to you the truth, as well as an admonition and a reminder for the believersâ€
[Hood 11:120]
5 Keeping away from everything that reminds us of sin and calls us to it.
6. Knowing all types of Shirks including big and small that you mentioned and others and refraining from those by doing the above and seeking refuge to Allah. Thus, in general, we can increase our faith.
Finally, "Do not feel weak before your enemy, and do not let him gain any power over you. Seek the help of Allah and do not feel helpless – as Your Prophet (peace and blessings of Allah be upon him) has enjoined you. Remember that “ever feeble indeed is the plot of Shaytaan (Satan)†[al-Nisa’ 4:76].
O Allaah, make faith dear to us and make kufr (disbelief), evildoing and sin hateful to us, and make us of those who are rightly-guided.
May Allah reward you for all your efforts especially for the last posting, an excellent one, indeed.