Absolute bliss, eternal-joy is the ultimate goal of the Jeev(Soul) and it can be attained only when Jeev can get rid of illusory potency Maya. There are three paths possible for reaching the destinations: Karma Yoga, Gyan-Yoga and Bhakti-Yoga. There are five classical checks to ascertain if a path is true path or not, which are as follows:
Anvay: It should let you reach the goal of absolute bliss(Parmananda.)
Is the path for everyone?
Is there any dependency(on other paths)?
Will it give an eternal goal or it gives a temporary attainment?
Karma-Kanda--the way of Karma fails in its very first check(Anvay) itself , i. e. it could give you Swargaloka(heavenly abode) at max, that too if you take utmost care all your life, otherwise this path causes your fall into lower realms.
Jnana-Yoga also fails in the very first check because it can confer knowledge of 'Self'(Atmajnana) at most. It cannot even confer Moksha, leave alone absolute bliss. Moreover it fails in the third check as well--it's not for everyone. Adi-guru Shankaracharya has suggested that a person possessing four virtues should approach the way of Jnana--the first virtue is control on mind--which is impossible for almost everyone.
It has been said for the Jnana-Yoga.
"Gyan ka panth kripaan ki dhara..."
[ The path of knowledge is like sword's edge...]
Now we discuss about Bhakti-Yoga. Padma Purana says that everyone has the right to walk the path of Bhakti. It's not just a moral and pious man but also all of the immoral people who have right to do Bhakti. Valmiki was a dacoit but he attained Moksha by chanting 'Mara, Mara..' because he was unable to even say word 'Ram.'
Jnani as well as ignorant has right to do Bhakti. All they have to do is to create an attachment for God. This might be even with a feeling of enmity for God. Those who are libertaed from Maya and those who are under its sway have equal right to chant God's holy names. Those who are Mumukshu( want nothing else but 'Moksha'(liberation)) and those who are entangled in worldly pleasure have equal right of listening Ram's and Krishna's stories.
Every material can be used to worship Krishna, unlike other deities who need specific materials in specific quantities.
Reference: Bramh, Jeev and Maya lecture series by Kripaluji part 25