What reason do you have to believe in God apart from being fearful of God?

One reason to believe in God is that Intelligent Design, logically, makes more sense than believing in abiogenesis and evolution as the cause of the world and all its living entities.

It’s natural to fear a superior power. That’s why people of yore worshiped and respected nature. There is a saying in Danish - only a fool does not fear the ocean. In the Bhagavat Purana it’s explained that the first step in God-realization is to see God in nature.

Once you get to know God, however, the natural fear of Him dissipates, and is replaced by love and appreciation for Him.

To love someone, you certainly have to know that person, and to that end Krishna descends regularly (every 4 billion years, in fact) to planet earth in order to reveal His pastimes and personality.

Actually, God hardly cares what you believe in. God wants you to know Him, so He can exchange love with you. Besides, love of God is what everyone is looking for, anyway, since it’s the only love that does not end in frustation and lamentation. We may relate to and love another body and mind, but only love of God can satisfy the soul. Eternal love is what we really want, and only God can satisfy that. Only love of God lasts forever.

Krishna says:

The sages, knowing Me as the ultimate purpose of all sacrifices and austerities, the Supreme Lord of all planets and demigods and the benefactor and well-wisher of all living entities, attain peace from the pangs of material miseries. —Bg 5.29

Srila Prabhupada explains:

The conditioned souls within the clutches of illusory energy are all anxious to attain peace in the material world. But they do not know the formula for peace, which is explained in this part of the Bhagavad-gita.

The greatest peace formula is simply this: Lord Krishna is the beneficiary in all human activities. Men should offer everything to the transcendental service of the Lord because He is the proprietor of all planets and the demigods thereon. No one is greater than He. He is greater than the greatest of the demigods, Lord Shiva and Lord Brahma. In the Vedas the Supreme Lord is described as tam isvaranam paramam mahesvaram.

Under the spell of illusion, living entities are trying to be lords of all they survey, but actually they are dominated by the material energy of the Lord. The Lord is the master of material nature, and the conditioned souls are under the stringent rules of material nature. Unless one understands these bare facts, it is not possible to achieve peace in the world either individually or collectively.

This is the sense of Krishna consciousness: Lord Krishna is the supreme predominator, and all living entities, including the great demigods, are His subordinates. One can attain perfect peace only in complete Krishna consciousness.

This Fifth Chapter is a practical explanation of Krishna consciousness, generally known as karma-yoga. The question of mental speculation as to how karma-yoga can give liberation is answered herewith.

To work in Krishna consciousness is to work with the complete knowledge of the Lord as the predominator. Such work is not different from transcendental knowledge. Direct Krishna consciousness is bhakti-yoga, and jnana-yoga is a path leading to bhakti-yoga. Krishna consciousness means to work in full knowledge of one's relationship with the Supreme Absolute, and the perfection of this consciousness is full knowledge of Krishna, or the Supreme Personality of Godhead.

A pure soul is the eternal servant of God as His fragmental part and parcel. He comes into contact with maya (illusion) due to the desire to lord it over maya, and that is the cause of his many sufferings. As long as he is in contact with matter, he has to execute work in terms of material necessities.

Krishna consciousness, however, brings one into spiritual life even while one is within the jurisdiction of matter, for it is an arousing of spiritual existence by practice in the material world. The more one is advanced, the more he is freed from the clutches of matter.

The Lord is not partial toward anyone. Everything depends on one's practical performance of duties in an effort to control the senses and conquer the influence of desire and anger.

And, attaining Krishna consciousness by controlling the above-mentioned passions, one remains factually in the transcendental stage, or brahman-nirvana. The eightfold yoga mysticism is automatically practiced in Krishna consciousness because the ultimate purpose is served.

There is gradual process of elevation in the practice of yama, niyama, asana, pratyahara, dhyana, dharana, pranayama, and samadhi. But these only preface perfection by devotional service, which alone can award peace to the human being. It is the highest perfection of life.